3.1 Climate

In 2003, climate in the Three Gorges reservoir area was continuously relatively warm with rainfall a little more. The temperature in the middle and west part of the reservoir area was obviously higher than previous years and the east part kept the level of normal years. The climate was relatively warm in all the four seasons, especially in winter. Rainfall was relatively much in winter and spring, and less in summer and autumn. In regional distribution of rainfall, the west part is relatively less and the middle and east part relatively much. There were no large area heavy disasters in flood season. Foggy days of the reservoir area were mainly concentrated in autumn and winter. The average foggy days were less than normal years. The average wind speed in the Three Gorges reservoir area was lower than normal years. In all stations, change of average wind speed was not much.

Table 3-1 Monitoring Results of Meteorological Elements in Meteorological Stations in the Three Gorges Reservoir Area in 2003

Name of station	Average Temperature (℃)	Comparative Humidity (%)	Rainfall (mm)	Evaporation (mm)	Average Wind Speed (m/s)	Sunshine Hours (h)	Foggy Days (d)	Thunder Storm Days (d)
Chongqing	18.9	80	1033.2	563.4	1.7	878.5	25	27
Changshou	18	81	1078.6	1140.7	1.4	1128	40	28
Fuling	18.7	79	1168.1	706.9	0.3	1144.4	79	31
Wanzhou	18.7	80	1461.2	627.4	0.6	1272.5	19	33
Fengjie	18.1	74	1366	718.9	1.5	1356.4	5	23
Wushan	18.5	73	1179.5	1085.1	1	1358.3	5	30
Badong	17.1	73	1113.5	1463	1.8	1239.8	69	41
Zigui	17.9	78	1014.8	1306.6	0.8	1429.2	0	26
Bahekou	16.6	81	1220.7	1135.3	1.5	1025.8	0	29
Yichan	16.8	79	1240.6	1219.7	1.3	1078.7	19	32

The average rainfall in the reservoir area was 1184mm, nearly 10 percent points more than normal years. Its regional distribution features were: relatively less in the west part and normal or relatively much in the mid east part. The most rainfall was found in Wanzhou, reaching up to 1,461.2mm; the rainfall in Zigui was the least, just 1,014.8mm. Compared with normal years, the rainfall was 20 percent points more in Wanzhou and Fengjie of the middle part and 10 percent points less in Chongqing and Changshou of the west part. In time distribution, the average rainfall of the reservoir area was relatively much in winter of 2002/2003 and spring of 2003, and relatively less in summer and autumn.

The rainfall distribution took a feature of single peak. The peak was in July with average rainfall reaching 218.8mm, 25 percent points more than the same period of normal years. The average rainfall in autumn in the reservoir area was 20 percent points less than normal years. The spatial distribution was uneven in different stations and seasons, with drought occurring in winter and summer and low temperature and unbroken overcast rainy days found in spring and autumn in some areas.

Figure 3-1 Rainfall Distribution Curve in June, July and August 2003 in the Three Gorges Reservoir Area

In 2003, the average temperature in the Three Gorges reservoir area was 18.1℃ 0.6℃higher than normal years and 0.2℃ higher than 2002. The change of temperature was within the actual range of normal years. As shown by the results of statistics and analysis of the temperature anomaly changes from June to November of successive years in the reservoir area and the temperature climate background area (Hubei, Sichuan and Chongqing), the trend of temperature change in the reservoir area was quite consistent with that of the background area. Water storage exerted no obvious influence to the change of temperature of the reservoir area. The spatial distribution feature of temperature in 2003 was: normal or 0.1-0.2℃ lower in the east part; 0.3-0.7℃ higher in the middle and west parts. The temperature of Fengjie was 1.9℃ higher than normal, the most obvious change. In time distribution, the temperature was relatively higher in all the four seasons. The average temperature of the reservoir area was 0.2-0.4℃ higher than the same period of the normal years in each season. The change to warm was the most obvious in winter, up to 1.1℃ higher than normal on average.

Figure 3-2 Changes for Years of Temperature Anomaly from June to November in the Three Gorges Reservoir Area and Its Background Area

In 2003, the average wind speed in the Three Gorges reservoir area was 1.1 m/s, 0.2 m/s lower than normal years. In all stations, seasonal changes and monthly changes of average wind speed were not much.

Average foggy days in the Three Gorges reservoir area numbered 29 days, 9 days less than normal years. The spatial and temporal distribution features were: foggy days in the west part were more than those in the east part; and in autumn and winter over those in spring and summer. Foggy days in most part of the reservoir area were obviously less than normal years. Except in Fuling, foggy days in the area west of Wushan were just equal to or less than half of those in normal years. As part with the least foggy days in the reservoir area, Zigui and Bahekou had not seen a single foggy day in two successive years. There was no obvious change in number of foggy days after the reservoir starting to store water.

The average comparative humidity in the Three Gorges reservoir area was 77%, close to that of normal years. The average comparative humidity at each station was 73-81%. Compared with normal years, the humidity was 6-7% higher in Wushan and Zigui but normal in other stations. The average evaporation in the Three Gorges reservoir area was 981mm, over 20% less than that of normal years. The regional distribution feature was going down from the east to the west.

In 2003, major meteorological disasters in the Three Gorges reservoir area were heavy fog in winter, periodical low temperature and continuous rain in spring and autumn, drought in spring, high temperature and drought in summer, and geological disasters like flood, waterlogging and landslide caused by strong convective weather like rainstorm, strong wind and hails.

In the spring and autumn, some places in the Three Gorges reservoir area once occurred low temperature and continuous rain, exerting impact on the plants to be harvested in summer and the spring plantation activities and worsening the crop pests and diseases. In mid May, the whole area of Chongqing suffered 5-7 continuous rainy days, causing production losses or no harvest in some places.

In the spring and summer, drought occurred in the Three Gorges reservoir area, exerting bad impact on the growth of crops and the life of local people. Among others, west part of the reservoir area suffered continuous drought from winter to spring. The drought situation in some counties and cities under the jurisdiction of Chongqing Municipality was serious, causing heavy losses of the crops sown in spring, spring silkworm and vegetables because short of water and difficulty in drinking water supply for hundreds of thousand people and big livestock. Some water consuming enterprises had to stop production. From late of July to middle of August, continuous high temperature and drought occurred in most part of the reservoir area. Such weather even continued to late of August in several places. Among others, in Fengdu, Fengjie, Wanzhou, Shizhu, Rongxian, Yongchuan and Shapingba etc. under the jurisdiction of Chongqing Muncipality, the direct economic losses caused by drought exceeded 160 million yuan.

In spring, summer and autumn, strong convection weather occurred frequently in some places of the Three Gorges reservoir area, causing a number of meteorological disasters induced by rainstorm, heavy wind and hail. From March to May, the reservoir area saw at least 4-6 times of strong convection weather. Heavy rainstorm, strong wind and hail damaged houses and crops and blocked communications, causing heavy economic losses. Among others, Chadianzi and Lucongpo saw a heavy hail thick up to 2 inches from March 31 to April 1. The heavy rainstorm caused mountain torrents and landslide. From April 16 to May, Wushan County, Jiangbei District, Liangping County and Wanzhou District of Chongqing Municipality were struck one after another by rainstorm, thunderstorm and hail, which caused geological disasters including landslide and mud-rock flow etc.

3.2 Terrestrial Plants

As shown by the results of summary analysis of plant species in the Three Gorges reservoir area made in 2003, there were 6,088 species of tracheophyta including more than 1,100 classes under species (subspecies, varieties and deformities), respectively belonging to 208 families and 1,428 genus, accounting for about 20% of the national total, among which the species of seed plants account for 22% of the national total. No new plant species was discovered. According to preliminary analysis, forest vegetation in the Three Gorges reservoir area could be classified into 15 community groups and 76 communities; the shrub vegetation can be classified into 5 community groups and 16 communities.

As shown by the results of tracking monitoring of the ancient trees in the Three Gorges reservoir area, the overall status was basically stable. There were 4,394 ancient trees older than 100 years belonging to 135 species in the reservoir area.

3.3 Terrestrial Animals

There are 561 species of terrestrial spinal animals in the Three Gorges reservoir area respectively belonging to 4 classes, 29 orders, 83 families and 285 genus.

As shown by the result of waterfowl monitoring investigation in the winter, great change had occurred in distribution, species and quantity of overwintering waterfowls in the area affected by the 139m water level (the main navigation channel of the Yangtze River and some tributaries) after the second stage of water storage of the Three Gorges Project construction. The most obvious change occurred in the main navigation channel of the Yangtze River. In the section affected by the water level (from Zhongxian County to Maoping, Zigui) the quantity of waterfowls dropped sharply with the eye-caught quantity less than 10% of that before water storage. There was also change in species. Among natatories, only a few species could be seen, including mallard, anas poecilorhyncha, mandarin duck and cotton teal etc., most of which occasionally appeared at the estuaries of the tributaries and near town ports. The Tadorna ferruginea and Mergus merganser etc. that used to be seen had disappeared. A new species of natatores as newly recorded bird in the Three Gorges reservoir area - Melanitta fusca appeared in the river section from Maoping, Zigui to Xiangxi estuary. In the channel area of 4 tributaries of the Yangtze River investigated, species and quantity of waterfowls had increased rather obviously, but just limited to a few species including grebe (a kind of waterfowl catching little fish in relatively deep water).

The Daning River in Wushan Country is one of the main habitats of mandarin ducks, which belong to the second-class national protected animals. According to the result of the monitoring investigation, quantity of mandarin ducks had no obvious change in Daning River area.

3.4 Fishery Resources and Environment

3.4.1 Fishery resources

In 2003, the natural fishing catch in the Three Gorges reservoir area, the section down the dam, Dongting Lake, Poyang Lake and the estuary area was 69,705 tons, 11% less than that of 2002. In Yunyang section, Jianli section and Wuxue section of the reservoir area, the fry run-off amount of the four major home fishes dropped at different levels; tapertail anchovy and Chinese turtle crab rose to some extent; and output of eel rose by a big margin.

Reservoir area: in 2003, the natural fishing catch in the Three Gorges reservoir area was 2,973 tons, a little less than that of 2002. The composition of the catch was 614 tons of largenmouth bronze gudgeon, 581 tons of bronze gudgeon, 323 tons of common carp, 274 tons of river Parasilutus asotus, 274 tons of Pseudobagrus, 153 tons of Leiocassis longirostris, 146 tons of grass carp and 90 tons of silver carp.

Monitoring of fishing catch showed that six species of fishes including bronze gudgeon, largemouth bronze gudgeon, common carp, river Parasilutus asotus, Pseudobagrus and Leiocassis longirostris accounted for 72% of the total catch, less than the percentage of 2002, but remaining the major economic fishes in the reservoir area.

Section down the dam: in 2003, the natural fishing catch in the section down the dam was 2,450 tons, a little less than that of 2002. The composition of the catch was 1,078 tons of bronze gudgeon, 353 tons of river Parasilutus asotus, 200 tons of Pseudobagrus, 217 tons of common carp and 135 tons of the "four major home fishes".

Monitoring of fishing catch showed that bronze gudgeon, river Parasilutus asotus and common carp accounted for 67% of the total, being the main economic fishes in section down the dam. Biological composition of the catch showed that river Parasilutus asotus, Leiocassis longirostris and bronze gudgeon caught were small and young.

Spawning sites of the "Four Major Home fishes": fry run-off amount of the "four major home fishes" in Yunyang section of the reservoir area, Jianli section down the dam and Wuxue section were monitored synchronously in June 2003. The results showed that at the same time of realizing the three major targets of storing water, opening navigation and generating power, spawning and breeding of the "four major home fishes" were also affected negatively. The fry run-off amount of all the "four major home fishes" dropped at different degrees.

In may and June 2003, the fry run-off amount of the "four major home fishes" in Jianli section was 406 million tails, 21.3% of 2002; that in Yunyang section was 290 million tails, 81.5% of 2002; and that in Wuxue section was 525 million tails, 23.6% of 2002.

Dongting Lake: in 2003, the total catch of the entire lake was 29,516 tons, 9.4% lower than that of 2002. There were 45 spawning sites of common carp and crucian carp, covering an area of 290.8 km2. There were 196,000 tails of spawning common carp, weighting at 353 tons and their spawn amount at 5.331 billion, 8.8%, 9.0% and 11.5% less than 2002 respectively. There were 271,000 tails of spawning crucian carp, weighting at 101 tons and their spawn amount at 3.829 billion, 9.1%, 9.8% and 2.7% less than the previous year respectively.

There were 34 feeding sites, covering an area of 751 km². Among them, 13 were in east Dongting Lake, covering 449 km²; 16 were in south Dongting Lake, covering 119 km² and 5 were in west Dongting Lake, covering 183 km². Main fishes in the feeding sites were common carp, silver carp, fathead, snail carp, grass carp, river Siniperca chuatsi and Parasilurus asotus and the amount of the feeding community was 6.624 billion tails.

Poyang Lake: the natural fishing catch of the entire lake in 2003 totaled 33,500 tons. There were 33 spawning sites, covering an area of 433 km². The spawn amount was 4.897 billion.

The area of feeding sites in the lake area was 460 km², 140 km² less than 2002. The feeding sites were mainly distributed in the middle part and the south part of the lake area. Main fishes in the feeding sites were common carp, crucian carp, snail carp, grass carp, silver carp, fathead, Siniperca chuatsi and river Parasilurus asotus etc.

Estuary area: in 2003, biological indicators of tapertail anchovy on length and weight all had no much difference. The total average output of individual ship in the entire flood season was 34.1% higher than that of 2002 and the total average value of individual ship in the entire flood season was 11.6% lower than that of 2002. The total catch was 1,256.88 tons, much higher than that of 2002.

Biological indicators of parent crabs were obviously higher than 2002. Average weight was 168.2g; average shell length and width were 62.87mm and 70.32mm respectively.

In 2003, 1,487 of eel catching licenses were issued in flood season, a little more than 2002 (1,340). The total output was 8,896.59 kg, much higher than that of 2002. Average indicators of individual ship were also higher than normal years.

3.4.2 Fishery environment

In 2003, seven monitoring stations (Yibin Station, Banan Station, Wanzhou Station, Jingzhou Station, Yueyang Station, Lake Outlet Station and Estuary Station) were set up in the mainstream of the Yangtze River, Dongting Lake and the estuary area to monitor the water quality of key fishery water bodies in the Yangtze River basin, and to make water quality evaluation based on the Fishery Water Quality Standard (GB11607-89) and watershed functional grade evaluation of the items prescribed in the Standard according to the Water Quality Standard for Surface Water Environment (GB3838-2002). The results showed that water quality of the key fishery water bodies in the Yangtze River basin was sound on the whole, which generally could meet the growing and breeding requirements of fishes. But parts of the water bodies were polluted to some extent. The major pollutants were oil, volatile phenol, non-ion ammonia and total phosphorous.

The major pollutants in the three important fishery water bodies of Yibin, Banan and Wanzhou in the upper reaches of the Yangtze River were copper, oil, volatile phenol and total phosphorous. Among them, the main pollutant in Yibin was copper, 100% over the standard; the main pollutants in Banan were total phosphorous, oil and volatile phenol; and the main pollutant in Wanzhou was total phosphorous.

The major pollutants in the three important fishery water bodies of Jingzhou, Yueyang and the Lake Outlet in the middle reaches of the Yangtze River were non-ion ammonia, oil, copper and total phosphorous. Compared with 2002, the pollution degree of copper and non-ion ammonia in Jingzhou fishery water body was decreased. In Yueyang fishery water body, only non-ion ammonia exceeded the standard in rearing period; pollution of copper was a little lightened and the pollution of total phosphorous still existed. The monitoring values of copper and zinc in the Lake Outlet fishery water body exceeded the standards of fishery water quality.

Results of water quality monitoring on the spawning sites of the Four Major Home fishes in the section from Yichang to Chenglingji of the Yangtze River in May and June of 2003 indicated that: the major pollutants affecting the water quality were oil and non-ion ammonia. In part of the water bodies in Zhicheng and Jianli Sanzhou, non-ion ammonia exceeded the standard at a rate of 33.3%. Oil pollution in Jianli Sanzhou exceeded the limit to Grade III of surface water environmental quality with exceeding rate at 100%. Compared with the situation in 2002, pollution of copper, zinc and lead was a little lightened.

Results of water quality monitoring on Yichang spawning sites of Chinese sturgeon (Acipenser sinensis) in September and October of 2003 indicated that: water body pollution of non-ion ammonia in the core of Chinese sturgeon spawning site between Dajiang Power Plant and Miaozui exceeded the standard at a rate of 5.9%. Oil pollution was at same level of 2002. Pollution degree of copper, cadmium and mercury reduced a little. The monitored value of dissolved oxygen was obviously higher than the same period of 2002.

Water quality in the fishery water bodies of Dongting Lake was improved as a whole compared with the situation of 2002. The major pollutants were copper, total nitrogen and total phosphorous. Copper exceeded the water quality standards in rearing period and the exceeding rates in breeding period and overwintering period were 37.5% and 28.6% respectively. Both total nitrogen and total phosphorous exceeded the limit to Grade III of surface water environmental quality standard at deferent degrees in the three functional periods.

In estuary area of the Yangtze River, volatile phenol and total phosphorous all exceeded the limit value of GradeⅡsurface water environmental quality standard in eel season, tapertail anchovy season and winter crab season. Compared with the situation of 2002, pollution degrees of oil, mercury and copper dropped a little.

3.5 Peculiar Fishes and Rare Aquatic Animals

3.5.1 Peculiar fishes in the upper reaches of the Yangtze River

In 2003, 63 species (sub-species) of fishes in total were collected in Yibin section and Hejiang section in the upper reaches of the Yangtze River, 26 species less than 2002. Among them, 36 species were collected in Yibin section and 55 species in Hejiang section, 7 and 23 species less than 2002 respectively.

14 species of peculiar fishes were collected  in Yibin section and Hejiang section of the Yangtze River, accounting for 32.6% of all the peculiar fishes affected by the Three Gorges Project. Among them, 7 species were collected in Yibin section and 13 species were collected in Hejiang section. Compared with the situation of 2002, 10 species of peculiar fishes decreased in the two sections. Among them, 6 species decreased in Yibin section, including Paracobitis potanini, Botia reevesae, Rhinogobio cylindricus, Gobiobotia nudicorpa, Schizothora chongi and Liobagrus marginatoides. 1 species Platysmacheilus nudirentris increased in this section. 7 species decreased in Hejiang section, including Paracobitis potanini, Platysmacheilus nudiventris, Abbotina obtusirostris, Gobiobotia nudicorpa, Schizothora chongi, Liobagrus marginatoides and Sinogastromyzon sichangensis.

3.5.2 Rare fishes

As observed in the breeding process of Chinese sturgeon spawn got from the intestine of bottom layer fishes, Chinese sturgeon spawned only one time in the autumn of 2003, which was approximately from midnight of November 5 to early morning of November 6, just in a short period and a small scale. The spawning site was located between the area of the Three Gorges dam's flood discharge gate and Zhenchuanmen section of the Yangtze River. The concentrated spawning site was located in the 3 km river section from the flood discharge gate area to Yichang Shipyard and then to the river center and the deep slot section to the left bank near material dock on the upper reaches of Miaozui.

Spawn-eating fishes had been eating spawn of Chinese sturgeon till November 11. These spawn-eating fishes included largemouth bronze gudgeon, bronze gudgeon, Pseudobagrus vachelli, Rhinogobio ventralis Sauvage, Rhinogobio cylindricus, Leptobotia elongata, Leiocassis crassilabris, Gobiobotia filifer and Leiocassis longirostris. Among them, Pseudobagrus vachelli had the highest capacity for eating spawn. The individual capacity was 1-191 grains and the average 61.7 grains. The next was bronze gudgeon, with individual capacity of 1-89 grains and the average 18.6 grains. The following was Rhinogobio ventralis Sauvage, with individual capacity of 8-25 grains and average 16 grains.

In 2003, one tail of Psephurus gladius and one tail of Myxocyprinus asiaticus were mistakenly caught within the area of Yibin City. The Psephurus gladius, a female, was 352cm long and weighted 150 kg. Since it was wounded, experts rescued it in Yibin and released it to the Yangtze River after installing an electronic tracing equipment on it. On January 30, 2003, it disappeared. The Myxocyprinus asiaticus was about 140 cm in length and weighted 35 kg. It failed to respond to save and medical treatment and was then made as a specimen.

In 2003, mistake catch of the rare fishes - Acipenser dabryanus and Psephurus gladius did not happen in the section from Shangzhongba in Jiaotan Village in Hejiang to Tongqianwan in Wanglong Village (about 60km) in the upper reaches of the Yangtze River. In mid April, one tail of Myxocyprinus asiaticus with 95cm long was mistakenly caught. After several days, it died because it was wounded too seriously. Then it was made as specimen.

In 2003, No activity of Psephurus gladius was observed in Yichang section in the middle reaches of the Yangtze River. According to the report, on December 11, 2002, one tail of female Psephurus gladius was mistakenly caught. It was about 15-25 years old, 330cm long and weighted at 117kg. It failed to respond to the emergency treatment and died. Postmortem examination showed that this Psephurus gladius had spawned one time. There were still about 1 million grains of spawn left in the abdominal cavity. This had been the first time to find such kind of fish in the Yangtze River section under Gezhou Dam since 1995.

3.6 Agricultural Ecology

3.6.1 Ecological environment of agriculture fields

In 2003, survey was conducted on 181 towns and villages in 19 counties in the reservoir area with the same survey base as 2002. Investigation results showed that along with the water storage reaching up to 139m and the agricultural restructuring, agricultural planting and sowing fields dropped greatly in the area. Backup wasteland suitable for agriculture was not much and reversion of slope farmland was sped up. Re-cropping index of farmland was high and agricultural production still concentrated on grain crop cultivation, but the percentage of economic crops was increasing year by year. Soil fertility of agricultural fields in the reservoir area was at middle level and its heavy metal content was normal.

In 2003, agricultural acreage in the reservoir area was 209,066 hectares, 9.0% less than the 232,162 hectares in 2002. Total sowing area in the reservoir area was 531,599 hectares, 6.6% less than that in 2002. Among these, the area of grain crops was 390,105 hectares and that of economic crops was 141,494 hectares, accounting for 73.4% and 26.6% of the total respectively. Compared with 2002, the proportion of economic crops was raised because the area of orange plantations increased and that of grain crops decreased.

In 2003, surveys on the cultivation of slope farmland showed that ecological rehabilitation focused on farmland reversion to forest and grassland was continuously carried out in 11 counties and cities in the reservoir area. The area of slope farmland over 25^o reversed to forest and grassland totaled 4332.7 hectares. In terms of cultivation types, paddy fields mainly grew crops with two harvests per year, accounting for 61.3%, basically the same as in 2002. The arid land mainly grew crops with three harvests per year, accounting for 65.0%, a little less than that of 2002. Because cropping index of farmland was high and farming activities were frequent in the reservoir area, slope farmland was still the main factor causing water and soil erosion.

In 2003, monitoring results of 44 representative fixed soil monitoring stations of paddy fields and arid fields showed that soil contents of nitrogen, phosphorus and potassium were basically the same as those of 2002 and contents of heavy metals were within the background value and attained the first level standard of the soil environmental quality. The farmland had not been polluted.

3.6.2 Investigation on the influence of orange belts

In 2003, the results of monitoring and investigation on the 181 towns and villages in the 19 counties in the reservoir area showed that: orange cultivation area was expanded and orange production in the reservoir area was increased. No abnormality was discovered by soil examination of the orange belts.

The orange cultivation area in the reservoir area was 31,626 hectares, 14.9% more than that of 2002. Total yield was 316,800 tons, 17.8% more than that of 2002. Yield per hectare was 10,017kg, a little higher than that of 2002.Investigaion on yield proportion of oranges of different qualities showed that the first level, second level and third level oranges accounted for49.8%, 35.2% and 14.9% respectively. Compared with 2002, there was no much change.

Monitoring results on the fixed soil monitoring spots in orange belts showed that the contents of total nitrogen, total phosphorus, total potassium, and alkali dissolved nitrogen, quick-acting phosphorus and quick-acting potassium didn't change much. The contents of heavy metals were within the range of background value and attained the first level standard of the soil environmental quality.

3.6.3 Rural energy

The results of monitoring and investigation on 181 villages and towns in the 19 counties of the reservoir area in 2003 showed that: the energy in the rural areas still mainly depended on the direct combustion of fuel wood and straw. Direct combustion of fuel wood accounted for the largest proportion, about 40.6% of the total. The proportion of straw combustion, small coal kilns, small hydropower and biogas was 37.3%, 17.5%, 1.2% and 3.4% respectively.

In 2003, investigation on the number of biogas pools and biogas production amount in the rural areas showed that popularization rate of rural biogas had been raised, mainly because of the large-scale spreading of bio-energy (biogas) bonded ecological homestead construction and high-efficiency eco-agricultural construction in the reservoir area. In the 1.085 million rural households in the reservoir area, there were 76,742 biogas pools with an annual production of 28.945 million m3. There were 7.07 biogas pools per hundred households, with biogas production of 26.68 m3, rising in a large degree compared with 2002. But the proportion of bio-energy in rural energy structure was still quite low, just accounting for 3.4% of the total rural energy demand.

3.6.4 Insect pests of crops

In 2003, the results of monitoring and investigation on 181 towns and villages in the 19 counties in the reservoir area showed that: the extent of crop insect pest in the reservoir area was medium with total area affected by insect pests decreased significantly and actual losses lightened. No explosion and major harm of certain insect pest took place.

Total area affected by insect pests was 431,140 hectare·times, decreasing significantly compared with the situation of 2002; area controlled was 348,250 hectare·times; control rate was 80.8%; grain loss recovered was 146,378.3 tons; and actual loss was 40,348 tons. The base number of the snout moth's lava over the winter in the rice paddy fields in the reservoir area was 1,131 per hectare.

Table 3-2 Statistics of Main Crop Insects Pest in the Three Gorges Reservoir Area in 2003

Type of Insects Pest	Area Affected (hectare·times)	Area Controlled (hectare·times)	Control rate	Losses Recovered (t)	Actual losses	Extent of Pest
			(%)		(t)
Rice paddy bores	97500	103680	106.3	31630.4	5548.8	Medium to
						serious
Rice flying flea	37020	38210	103.2	25739	2533.8	Medium
Rice blast	19760	25550	129.3	24643.9	6485.6	Medium to
						serious
Sheath and culm blight of rice	33970	30020	88.4	10244.2	1899.1	Medium
Corn ring spot	7100	11170	157.3	722.9	401.4	Light
Wheat ibberellic disease	15510	11440	73.8	2335.7	1914.9	Light
Potato late disease	15230	13370	87.8	2281	589.6	Light
Sheath and culm blight of corn	20190	18530	91.8	5094.6	949.9	Light
Orange red and yellow spiders	27920	28230	101.1	8105.1	1584.1	Medium
Rats	156940	68050	43.4	35581.5	18440.8	Medium to
						serious

3.7 Geological Disasters

3.7.1 Earthquakes

In 2003, monitoring was made on the earthquakes occurred in the key monitored area of the Three Gorges (110°14′-111°05′E, 30°40′-31°10′N) and the area from the reservoir head to the middle (108°20′-112°00′E, 29°55'-31°45′N).

In 2003, 235 times of earthquakes occurred in the key monitored area. Among them, there were 165? times of 0.0≤ML<0.9 ones, 66 times of 1.0≤ML<1.9 ones and 4 times of 2.0≤ML<2.9 ones. The highest-level earthquake (ML=2.2) happened in Zigui on November 25. There were 541 times of earthquakes happened in the area from the head to middle of the reservoir area, including 287 times of 0.0≤ML<0.9, 220 times of 1.0≤ML<1.9, 33 times of 2.0≤ML<2.9 and 1 time of 3.0≤ML<3.9. The highest-level earthquake (ML=3.6) happened in Lichuan on November 14. The earthquakes in this year mainly spread along the belts of Wushan - Badong - Zigui, Yichang - Changyang. Earthquake intensity and frequency increased to some degree, which had obvious relation to water storage of the reservoir.

Figure 3-3 Earthquake Frequency in the Key Monitored Area of the Three Gorges in 2003

Figure 3-4 Earthquake Frequency in the Area from the Reservoir head to middle of the Three Gorges in 2003

3.7.2 Collapses, landslips and mud-rock flows

● Monitoring and early warning

In 2003, investigations of landslips, collapses and mud-rock flows were further carried out on the Three Gorges reservoir area. There were already 4,719 places experiencing landslips and collapses in total in the reservoir area. 1,216 places of them were under monitoring and early warning. On the basis of public monitoring and prevention on all these places, professional monitoring was carried out in 124 places, including GPS monitoring, RS monitoring and comprehensive tridimensional monitoring. All these efforts had made important achievement.

In 2003, under the influence of heavy rain and storm in flood season and water storage of the reservoir, part of the landslip bodies and slope in the submerged area sped up deforming. The monitoring and early warning system had played an important role, found out the potential danger in time and sent out alarm immediately. Local governments gave quick response and took effective measures to protect people's lives and properties. There were 14 places experiencing dangerous situation of landslips and collapses in Zigui County of Hubei Province, including 4 places successfully forecasted by the professional monitoring system and 10 places successfully forecasted through public monitoring and prevention mechanism. Safety of about 3,200 people was protected. The landslip and collapse monitoring and warning system in the non-backwater zone also made important achievement. For example, the successful forecast of the landslip in 345 Community of Taoping, Qukou in Chongqing's Kai County protected the safety of 410 people.

The landslip in Qianjiangping, Shaxi Town of Zigui County on the left bank of the Qinggan River, a south tributary of the Yangtze River (5 km away from the estuary) was a successful mode of the public monitoring and prevention mechanism. Fissures were found on the back edge of the slope on June 16, and the slope deformation became worse by July 12. Governments of the county and town took decisive measures in time to add 20 new monitoring spots and evacuated 1200 villagers and workers from 129 households and 4 enterprises. At 00:20 of July 13, a mud and rock layer, long about 1,200m, wide about 800m, with edge height difference over 300m, about 2400 ×104m3, slid into the river and formed a big dam. Because residents were evacuated in advance, personal casualties and property losses were reduced to the minimum.

● Assessment of geological safety

In order to provide a basis for the inspection and acceptance of the second stage of water storage and immigration project in the Three Gorges Project and further strengthen geological disasters control in the Three Gorges reservoir area, the Office of State Council Three Gorges Project Construction Committee entrusted the Ministry of Land and Resources to organize overall assessment on geological safety for the second stage of immigration project of the Three Gorge Project, i.e. assessment on the influence degree of major geological disasters including collapses, landslips and mud-rock flows to the safety of immigrant settlement areas and the key immigration projects.

Geological safety assessment was made with towns, townships and rural resident spots (more than 100 people, including professional facilities) as regional units and with major bridges and other important spots as engineering units of the assessment. The 12 counties (districts) in the lower stream of Fuling under the influence of the second stage of water storage were divided into 385 units (110 units in Hubei, 275 units in Chongqing). Through data review and on-the-spot investigation, there were 301 units (84 in Hubei and 217 in Chongqing) belonging to safe geological units or basically safe geological units, accounting for 78.2% of the total units; and there were 84 units (26 units in Hubei and 58 units in Chongqing) belonging to relatively poor safe geological units and unsafe geological units, accounting for 21.8% of the total units. Safe and basically safe geological units in the immigrant settlement areas (including reconstruction projects) accounted for 80%. Many rural residents settlement spots were located in relatively poor safe geological units and unsafe geological units.

The assessment believed that the geological safety status of the assessment units in counties (districts) of Chongqing Municipality would have not essential influence to the second stage of water storage. Local governments had adopted measures to the relative poor safe geological units and unsafe geological units. Water storage would have some influence to the landslip stability of some townships and towns in parts of Badong County, Hubei Province, but would not cause large scale deforming and destruction.

● Control and prevention projects

In order to ensure smooth progress of the Three Gorges Project construction and the safety of ecological environment in the reservoir area, The Programming on Geological Disasters Control in the Second Stage of Three Gorge Reservoir Area formulated by the Ministry of Land and Resources and Approved by the State Council required that before water stored in the 135m high dam by Jun 2003, 198 collapse and landslip control projects (56 projects in Hubei and 142 projects in Chongqing), 81 sections of collapsed bank protection (22 sections in Hubei and 59 sections In Chongqing) must be completed. In carrying out the program, both Hubei and Chongqing made some adjustment and actually completed 173 collapse and landslip control projects (44 in Hubei and 129 in Chongqing) and 74 sections of bank protection (59 sections in Hubei and 52 sections in Chongqing). Before the second stage of storing water in June 2003, Hubei and Chongqing had completed 100 collapse and landslip control projects and 59 sections of bank protection, integral projects or underwater parts, totaling 159 projects (or sections) including 24 projects (sections) in Hubei and 135 projects (sections) in Chongqing. Through overall inspection and acceptance at county (district) level and province (prefecture) level or sampling inspection and acceptance at state level, the entire project completed was qualified. All these projects played important roles in guaranteeing stability of the slump structures and the reservoir bank.

According to the instruction of Premier Wen Jiabao: "in the construction of the Three Gorges Project, we must respect the nature and protect the nature, adopt practical measures to permeate the whole process of construction with the strategy of sustainable development, try efforts to realize perfect harmony between the project and the nature" and "relevant departments should formulate and perform as soon as possible programming on greening belts around the reservoir, programming on geological disaster control in the third stage of the Three Gorges reservoir area and work plan of clearing of the floating matters on the Three Gorges Reservoir area and the upper reaches, further improving ecological environment of the reservoir area", the third-stage programming on geological disaster control was also coming on the way under the organization and leadership of the Ministry of Land and Resources while the tasks of second-stage geological disaster control closing to the end. On the basis of field verification on the new collapses and landslips, the collapses and landslips that need to be controlled as decided in the second stage and the bank section with poor stability, geological programming investigation and survey were made on 986 places of collapses and landslips as well as 358 km of reservoir bank. 957km² of 1:5000 topographic mapping measurement, 482km² of 1:5000 geological mapping measurement and 1,397km of geological profile survey were completed; 1,608 holes (drilling footage: 80,400m) and 402 shallow wells (drilling footage: 6,030m) were drilled; and 75,800m3of trenching and 1,816km of geophysical prospecting were completed.