3.1 Climate

The air temperature of the Three Gorges Reservoir area in 2004 was continuously higher than the average with precipitation close to normal years. The annual average temperature (AT) of the central and eastern part was evidently higher than that of usual level. While the annual air temperature of the western part was similar to normal level. In winter and spring, the air temperature of the region was obviously higher than the average level but slightly lower in summer and autumn. The average annual precipitation was above the average in the western part, same as usual in the central part but lower than the average in the eastern part of the reservoir area. Precipitation occurred more than the average level in winter and autumn, lower than the average in spring and same as usual in summer. During the wet season, there were not any large-scale and serious flood disasters. The annual average number of foggy days and average evaporation of the Three Gorges Reservoir area were less than the normal level. The annual average wind speed was slightly less than the average level with small or no change of wind speed at each typical weather station. Major climate disasters include storms, floods and its secondary geological disasters such as landslides and mud-rock flows, droughts, strong winds, hails, strong convective currents and heavy fogs.

Table 3-1 Monitoring results of meteorological items of each weather station of the Three Gorges Reservoir area in 2004

Station name	AT	RH	P	E	AWS	NHS	NFD	NT
	(℃)	(%)	(mm)	(mm)	(m/s)	(h)	(d)	(d)
Chongqing	18.4	78	1188.4	669.6	1.3	981.3	33	36
Changshou	17.6	83	1365.4	1083	1.2	1101.3	46	32
Fuling	18.2	77	1269.5	663.8	0.6	1073.2	74	37
Wangzhou	18.5	75	1314.9	697.3	0.7	1073.2	8	28
Fengjie	18.2	72	1153.3	819.4	1.5	1421.6	9	26
Wushan	18.7	66	1074.3	1456.7	0.6	1430.4	6	28
Badong	17.5	69	1094.6	1624.5	1.8	1505	29	34
Zigui	18.1	74	868.1	1437.1	0.9	1416.7	1	19
Bahekou	17.3	73	897.3	1331.9	1.7	1357	0	28
Yichang	17.8	73	950.7	1457.1	1.2	1264.7	15	38

Note: RH stands for relative humidity; P for precipitation; E for evaporation; AWS for average wind speed; NHS for number of hours with sunshine; NFD for number of foggy days; NT for number of thunder storms.

The annual average precipitation of the Three Gorges Reservoir area was 1142.1 mm in 2004, similar to normal level. The maximum precipitation occurred in Changshou, which was 1365.4 mm. The minimum precipitation was in Zigui with 868.1 mm. Compared with normal years, precipitation in regions west to Wangzhou was 10%～20% more than that of normal years. The precipitation from Fengjie to Badong remained at normal level. But the rainfall of Zigui and its east was 10%～20% less than the average level of normal years. The precipitation of the reservoir area was above-average in 2003/2004 winter, below-average in the spring, normal in summer and slightly higher in the autumn. The annual precipitation presented double peaks with one in May and the other in September, 190 mm and 176 mm respectively, which were 25% and 35% more than the average level of normal years. The special distribution of precipitation of the reservoir area at each weather station was not even in each season. In winter and spring, most areas to the west of the Three Gorges Reservoir had above-average precipitation with storms and floods in some of the area, while the areas to the east of the dam had drought in winter and spring. In summer and autumn, there were frequent strong convective currents in part of the reservoir areas with continual storms and floods. However, there were also other areas suffering from heat wave and drought in summer and stage drought in autumn.

The pH value of the precipitation in the reservoir area was 4.77 in 2004 with slight drop in rainfall acidity compared with that of 2003. Rainfall acidity was the biggest in the autumn, followed by winter, spring and summer.

Figure 3-1 Spatial distribution curve of the precipitation of the Three Gorges Reservoir area in June, July and August of 2004

The annual average temperature of the Three Gorges Reservoir area in 2004 was 18.1℃, same as in 2003 but 0.6℃ higher than the historical average level. The annual average temperature in eastern reservoir area had an evident rise, 0.1～1.0℃ higher than the historical average at the same period. Among them, the biggest increase of annual average temperature occurred in Yichang, which was 1.0℃. The annual average temperature change in the western part was slightly higher than the average level of the past years. In winter and spring, the average temperature was evidently higher than the historical average by 1.2℃ and 1.5℃ respectively. In summer and autumn, the average temperature had a little drop by 0.3℃ and 0.1℃ compared with the historical average in the same period. In time distribution, the maximum monthly temperature of the reservoir area was in July with 27.8℃, the minimum one in January with 7.2℃. The annual temperature gap was 20.6℃. When Yichang was used as control area, it was indicated that the temperature of the Three Gorges reservoir area was 0.4℃ up in winter and 0.5℃ down in other three seasons after the impoundment. The change trend of temperature of the entire Three Gorges Reservoir area in 2004 was the same as that of the background region (Hubei, Sichuan and Chongqing) with fluctuations falling into the normal change range. On the whole, the impoundment did not impose obvious impact on the temperature of the reservoir area.

Figure 3-2 Yearly change of the gap to annual average temperature of the Three Gorges Reservoir area and that of the background region

The wind of the reservoir area in 2004 was not strong with the average wind speed being 1.1m/s, down by 0.2m/s compared with the normal level. Both the seasonal and monthly changes of the annual average wind speed of each weather station were not big. However, there used to be gale at the speed≥17.0m/s in the reservoir area subject to strong convective currents.

The annual average number of foggy days of the reservoir area in 2004 was 24, 5 days less than in 2003 and 13 days less than the historical average. There were more foggy days in the western part than in the eastern part. And more foggy days occurred in autumn and winter than in spring and summer. But the number of foggy days in all four seasons was smaller than the historical average. Except for Fuling and Zigui where experienced 1.7 and 0.7 more foggy days than normal level, other weather stations monitored 4 ~ 27 less foggy days than the historical average. The annual foggy days of Wanzhou and Fengjie were less than 50% of the historical average. The biggest reduction occurred in Wanzhou, which was 44.6 days less than the historical average.

The annual average relative humidity of the reservoir area in 2004 was 74%, down by 2 percentage points than the historical average. It increased from the east to the west. Compared with normal years, Wanzhou had 6% decline in relative humidity, while other regions basically kept the same. The relative humidity was the maximum in autumn and minimum in spring with seasonal change bigger than that of 2003.

The annual average evaporation of the reservoir area in 2004 was 1100.9 mm, about 10% less than the historical average. The regional distribution of the evaporation was big in the east and small in the west. From Wushan to the west except Changshou being normal, most of the region had 30% ~ 40% less evaporation compared with the historical average. To the east except Yichang with 10% rise, most of eastern region had normal evaporation level. The evaporation of each season of Fuling, Wanzhou and Fengjie was 20% ~ 40% less than the historical average. The monthly average evaporation of the reservoir area in June, July and August ranged from 115 mm to 168 mm, down by 10% ~ 20% compared with the historical average.

Major climate disasters of the reservoir area in 2004 were storms and floods as well as secondary geological disasters resulting from floods such as landslide and mud-rock flow, drought, gale, hail, strong convective current and heavy fog.

Storms and floods mainly occurred in summer and autumn with the scale of regional or local. All weather stations affiliated to Chongqing Municipality recorded at least 131 storms from May to September. The disasters such as floods, landslide and mud-rock flow triggered by those storms had caused several billion yuan direct economic losses. For example, the first strong storm at regional scale along Chongqing section of the Yangtze River on 29th ~ 31st of May affected 5.667 million people in 21 districts (counties) with direct economic losses of 548 million yuan. Another strong regional storm hit the same area on 4th ~ 6th of September with the biggest intensity since 1982, affecting 23 districts (counties) with 82 dead and the direct economic losses of 2.123 billion yuan. The areas under the administration of Yichang City Government, which was in the eastern part of the Three Gorges Reservoir area, recorded 29 storms from May to August. They led to rapid rise of river flow, flooded farmland, and frequent landslides and mud-rock flows. According to Land Resources Bureau of Yichang, the geological disasters resulting from strong regional precipitation during May ~ July totaled 23 with direct economic losses of 18.84 million yuan.

Drought disasters mainly happened in late winter, spring, summer and autumn. The droughts in late winter and spring usually covered large area with relatively longer period. Yichang prefecture, which located in the eastern part of the reservoir area, experienced the worst continuous drought from January to April (winter and spring) in the history, leading to severe lack of impoundment in ponds and reservoirs, grim situation for the prevention of forest fires and serious impacts on spring sowing. Summer drought mainly occurred in Chongqing Municipality west to the Dam, lasting from July 22 to August 12. According to local statistics, 35 districts (counties) under the jurisdiction of Chongqing Municipal Government were subject to spring and summer drought with direct economic losses of 789 million yuan, 645 million yuan of which came from agriculture. Autumn drought happened in Yichang east to the Dam, lasting from late September to early November with both grain and commercial crops subject to adverse impacts.

Gales and hails often occurred in spring and early autumn. Chongqing suffered from at least 17 gale or hail attacks in February and from April to September with direct economic losses of 420 million yuan. Meanwhile, Yichang experienced at least 11 gales and hails with direct economic losses of 130 million yuan.

Heavy fogs mainly occurred in winter, 8 of them had significant impacts. The heavy fog during December 11 ~ 12 lasted quite long with wide coverage, making the visibility of some regions down to dozens of meters and bringing to the closure of airport and highways as well as shutting down of navigation route. In addition, a very big traffic accident occurred at No.239 provincial highway in E'zhou City due to a heavy fog, leading to 5 dead and 24 injured.

3.2 Terrestrial Plants

Researchers carried out analysis on plant species of the Three Gorges Reservoir area in 2004. They did not find any new plant species, indicating that plant species remain at the amount of 2003. There were 6,088 vascular plants in the reservoir area, which belong to 208 families and 1,428 genuses. Among them, 400 were pteridophyte belonging to 38 families and 100 genuses; 88 were gymnosperm belonging to 9 families and 30 genuses; 5,600 were angiosperm that belonged to 161 families and 1,298 genuses.

At present, there are 51 precious, rare and endangered plant species in the reservoir area, accounting for 13.1% of the total (388 species). Among them, 8 are endangered, 19 rare and 24 close to be endangered. Those rare and endangered plant species that live under 400 m above the sea level are mainly Magnolia, Machilus, Adiantum reniformevar sinense and wild soybean.

3.3 Terrestrial Animals

There were 561 terrestrial vertebrates in the Three Gorges reservoir area, including 103 species of beats, 390 species of birds, 36 species of reptiles and 32 species of amphibious animals. Among them, nine are Grade I national protected animals and 64 species are Grade II national protected animals.

During winter monitoring of water birds, Egretta alba were found at Pengxi River flowing across Yunyang and Kai County. This is the first time Egretta alb were found at the Yangtze River and its major tributary waters since such monitoring activities were carried out in 1999. In addition, the breeding places of such Class II animals under Special State Protection as Acipiter soloensis and Ketupa flavipes were found in the reservoir area under the jurisdiction of Hubei Government. The investigations found that there were some changes in community population and distribution of mandarin ducks (Class II animal under special State protection). Investigators had observed mandarin ducks at such places as the upstream of the tailwater of Meixi River in Fengjie County, Daning River of Wushan County and the section of the Yangtze River from Wushan Port-Zigui Maoping Port with increased community population.

3.4 Fishery Resources and Environment

3.4.1 Fishery resources

The total fishing amount of the Three Gorges Reservoir area, waters downstream the huge Dam, Dongting Lake, Poang Lake and estuary area in 2004 was 63,000 tons, 10% down compared with that of 2003. The fish fry flow of the "Four major home fishes" at Jianli Cross-section downstream the Dam continuously declined. There was a relatively dramatic reduction of the output of coilia mystus and eel fry in estuary area.

● Reservoir area

The total fishery catch of the Three Gorges Reservoir in 2004 was 2,369 tons, 20% down compared with that of 2003. If we calculated the catch of individual species in the light of species composition in the reservoir area,491 tons were large mouth bronze gudgeon, 429 tons were bronze gudgeon, 294 tons were pelteobagrus fulvidraco，210 tons were carp, 207 tons catfish, 108 tons grass carp and 92 tons silver carp.

The monitoring results showed that the six species including large mouth bronze gudgeon, bronze gudgeon, pelteobagrus fulvidraco, carp, catfish and grass carp accounted for 73% of the total fishery catch and were major commercial species of the reservoir area. However the size of catfish, large mouth bronze gudgeon and bronze gudgeon was still relatively small and their age was rather young. Among them, 92% of catfish were only one-year old.

● Waters downstream the Dam

The total fishery catch of the waters downstream the Three Gorges Dam in 2004 was 2,100 tons, a reduction of 14% compared with that of 2003. Among them, the capture of bronze gudgeon was 796 tons, catfish 551 tons, carp 184 tons, pelteobagrus fulvidraco 122 tons and the "Four major home fishes" 101 tons.

The catch monitoring results showed that bronze gudgeon, catfish and carp accounted for 73% of the total catch, which were still the commercial fish species in the waters downstream the huge Dam. However, the size of caught bronze gudgeon and catfish was smaller than the normal standard. Among the caught catfish, 70% were only one-year old.

● Spawning sites of the "Four major home fishes"

The fish fry runoff of the "Four major home fishes" at the Sanzhou Section in Jianli County in May ~ June of 2004 continuously decline to 339 million, down by 16.5% compared with that of 2003. This was only 13% of the baseline figure before the impoundment (1997～2002). In May of that year, there were only 37 million fry, only 11.6% of the minimum level of the historical same period (318 million fry in 2000) before the impoundment.

● Dongting Lake

The total catch of Dongting Lake was 26,000 tons in 2004, a reduction of 13% compared with that of 2003, 13,000 tons of which coming from the eastern part of Dongting Lake, 8,000 tons from the southern Dongting Lake, 5,000 tons from the western Dongting Lake, accounting for 49%, 31% and 20% of the total respectively.

There were 45 spawning sites for carp and crucian with total area of 277 km², 13 of them in the eastern part of Dongting Lake with an area of 139 km²; 26 in southern part of Dongting Lake with an area of 63 km², 6 of them in the western part of the Lake with an area of 75 km². The population of carp spawning communities were 175,000 weighing 296 tons, down by 10.7% and 16.1% respectively compared with that of last year. A total of 5.035 billion eggs were produced, similar to that of 2003. The population of egg-laying crucian carps was 378,000 weighing 110 tons, up by 39.5% and 8.9% respectively compared with that of 2003. A total of 4.198 billion eggs were produced, an increase of 10.3% compared with that of 2003.

There were 34 feeding sites in this Lake with a total area of 676 km². 13 of which were in eastern part of the Dongting Lake with an area of 108 km², 16 in southern part of the Dongting Lake with an area of 108 km², and 5 in eastern part of the Dongting Lake with an area of 164 km². The species of fish in those feeding sites were mainly carp, crucian, catfish, pelteobagrus fulvidraco, the "Four major home fishes", bighead and bream. The fish population in the Lake is 5.763 billion, 13% down compared with that of 2003.

● Poyang Lake

The total fish catch was 32,000 tons in Poyang Lake in 2004. There were 33 spawning sites for carps and crucians in the lake with an area of 230 km2, down by 47% compared with that of 2003. A total of 3.58 billion eggs were produced, a decrease of 27% compared with that of 2003.

The area where fish could seek feed was 430 km² in the Lake, a reduction of 7% compared with that of 2003. It was mainly distributed in the central and southern part of the Lake. The type of fish in the Lake were mainly black carp, grass carp, silver carp, bighead, carp, crucian, catfish and mandarin fish.

● Estuary area

The total catch of coilia mystus during the fishing season of 2004 was 748.36 tons. And the average catch of every ship during the fishing season was 3311.31 kg with the output of 30481.46 yuan, down by 40.5%, 34.1% and 29.2% respectively compared with that of 2003. The total fish resources was 795.79 tons with the instantaneous resource amount at the end of fishing season being 47.43 tons, down by 40.1% and 33.2% respectively compared with that of 2003. The average length of coilia mystus during the fishing season was 155 mm with average body weight of 14.44 g, up by 5.4% and 3.4% respectively compared with that of 2003.

During the fishing season, the total catch of parent Chinese turtle crabs was 1826.69 kg. And the average catch of every ship during the fishing season was 68.16 kg, down by 45.5% compared with that of 2003. The total fish resource was 47.47 tons with instantaneous resources of 42.64 tons at the end of the fishing season. The average shell length of the parent crabs during the fishing season was 62 mm with 67 mm in average width and 145.1 g in average weight, down by 1.4%, 4.7% and 13.7% respectively compared with that of 2003.

The total catch of eel fry during the fishing season was 5101.25 kg, a reduction by 42.7% compared with that of 2003. The average index of eel fry of every ship had an evident decline compared with that of the previous year. And the average output of each ship in the whole season was 70308.1 yuan, down by 25.7% compared with that of 2003.

3.4.2 Fishery environment

The authority organized the monitoring work on 17 water quality items of 7 major fishery waters (Yibin, Banan, Wanzhou, Jingzhou, Yueyang, Lake outlet and estuary) in the mainstream of the Yangtze River, Dongting Lake, Poyang Lake and estuary Area and carried out water quality assessment in line with the "Fishery Water Quality Standards (GB11607-89)" in 2004. The findings indicated that the overall water quality of major fishery waters of the Yangtze River Basin was good in 2004 and could basically meet the requirements for the growth and egg-laying of fishes. However, some waters were subject to pollution at some degree and major pollutants were petroleum, copper, non-ionic ammonia and volatile phenol.

In Guagongshan water area of Yibin, the concentration of copper exceeded water quality standard by 100% during the egg-laying, fattening and winter periods. In Xiaziliang water area of Banan, pollutants such as petroleum, volatile phenols, zinc and copper also exceeded water quality standard at different degree. Among them, the concentration of petroleum in 66.7% samples went beyond relevant standard in fattening period and in 100% samples over winter. The concentration of volatile phenol in 33.3% samples went beyond the standard in winter. The level of zinc of 100% samples exceeded the standard during both the egg-laying period and fattening period. The copper concentrations of 100% sample went beyond the standard during the spawning period. However, all monitoring items of the water area in Shaiwangba of Wanzhou did not go beyond the standards.

In Guanyinsi water area of Jingzhou, the concentration of petroleum of 66.7% samples went beyond the standard during fish fattening period and lead concentration of 16.7% samples went beyond the standard during winter. 

In Chenglingji water area of Yueyang, all monitoring items did not go beyond relevant standards. In water area of Lake outlet, petroleum concentration of 33.3% samples in egg-laying period and 100% samples in winter went beyond the standard. The concentration of non-ionic ammonia of 100% samples in fattening period and 33.3% in winter went beyond the standard.

All monitoring items of the egg-laying grounds of the "Four major home fishes" in Jianli monitoring site did exceed the standard during May and June. Each monitoring item of spawning sites of Chinese sturgeon in water area of Yichang did not exceed the standard in November.

The pollutants in fishery waters of Dongting Lake were copper and non-ionic ammonia. The concentration of copper of 18.2% samples in egg-laying period, of 18.2% samples in fattening period and 9.1% samples in winter went beyond the standard. And the non-ionic ammonia level of 18.2% samples went beyond the standard during egg-laying period.

The pollutants in fishery waters of Poyang Lake were copper and non-ionic ammonia, too. The concentration of copper of 100% samples went beyond the standard during both the egg-laying, fattening and winter periods. The non-ionic concentration of 100% samples went beyond the standard during the fattening period.

The pollutant of fishery waters in estuary area of the Yangtze River was volatile phenol and its concentration of 50% of the samples went beyond the standard during the fish season of coilia mystus.

3.5 Endemic Fish Species and Rare Aquatic Animals

3.5.1 Endemic fish species in the upper reaches of the Yangtze River

In 2004, samples of 100 species (sub-species) of fishes were collected in the upper reaches of Yangtze River (referring to the middle and lower reaches of Jinsha River, Hejiang section of Yangtze River and Xishui River, Wanzhou section of Yangtze River, Wujiang River), including 24 endemic fishes dominated by large mouth bronze gudgeon, Rhinogobio ventralis, Rhinogobio cylindricus and Schizothorax wangchiachii in terms of quantity. The middle and lower reaches of Jinsha River boasts 18 endemic species, the most diversified in all the river sections monitored. The diversity of endemic fish species diminished gradually down the mainstream of Yangtze River to only three species to the Wanzhou section.

According to the fish eggs collected, inferences had been made regarding the spawning sites of large mouth bronze gudgeon and Leptobotia elongata, two endemic species of fish with great quantity and extensive distribution: the spawning beds of large mouth bronze gudgeon in the middle and lower reaches of Jinsha River were mainly distributed in the river section between Jinanqiao and Shudi; the spawning sites of Leptobotia elongata were scattered in many places, among which those in the river section between Jinjiangqiao and Yupao River mouth as well as the Long River section were relatively larger.

3.5.2 Rare and precious fish species

The spawning sites of Chinese sturgeon remained in the river section between Gezhou Dam and Miaozui and was concentrated in the floodgate area of the Dam, the upper reaches of the river center area and the deep bed area of the river's left bank between Yichang Shipyard and the supply service wharf in Miaozui, totaling about 3 km. The Chinese sturgeons in this area laid their eggs on November 11, 2004, which is the latest over recent years. The spawning occurred in a large scale, and, compared with the previous year, it lasted longer. The breeding population of Chinese sturgeon mainly inhabited in the river section between Gezhou Dam base and Yanzhi Dam, about 2km's long and no less than 10m's deep in the water. The findings of Micro-satellite DNA mark study indicated that currently 90% of young Chinese sturgeons in the Yangtze River were the offspring from natural reproduction, which demonstrated that population from natural reproduction remained dominant in the Chinese sturgeon communities and the amount of artificial breeding was only supplementary.

The phenomena of egg-eating fish hunting for Chinese sturgeon eggs lasted until November 19. There were 9 species of such fish, namely large mouth bronze gudgeon, bronze gudgeon, Pelteobagrus vachelli, Rhinogobio ventralis, Rhinogobio cylindricus, Leptobotia elongata, Leiocassis crassilabris, Gobiobotia filifer and Leiocassis longirostris. Among these large mouth bronze gudgeons caught, 81.8% of them ate fish eggs, the highest among the fish species; the percentage of egg-eating for Pelteobagrus vachelli was the second, up to 76.2%. According to observation, bronze gudgeon devoured Chinese sturgeon fries occasionally.

In 2004, there was no record of accidental catching of Psephurus gladius, Chinese sturgeon, Acipenser dabryanus and Myxocyprinus asiaticus in the middle and lower reaches of Jinsha River. Seven cods were caught accidentally in Luzhou city in November, all being cultivated from other waters. Among the seven, three were raised temporarily. Three Myxocyprinus asiaticus caught accidentally in Luzhou River section were 115 cm, 120 cm and 123 cm in length and 17 kg, 33 kg and 20 kg in weight respectively. One of the three fishes was dead, and two others were returned to the Yangtze River. In Wujiang River, one Myxocyprinus asiaticus, 126 cm in length and 20.8 kg in weight, was accidentally caught and was then returned to the River. In the lower reaches of Wujiang River, no case of accidental catching of rare fishes had occurred. In the Wanzhou river section, one Myxocyprinus asiaticus weighing around 1kg was caught accidentally and was raised temporarily. In the Yichang river section, no Psephurus gladius and Acipenser dabryanus were found, neither was there any case of accidental catching of Myxocyprinus asiaticu. 17 parent Chinese sturgeon were caught for artificial breeding or ultrasonic tracking studies.

3.6 Agricultural Ecology

Surveys were conducted in 181 towns and villages of 19 counties (cities) in the Three Gorges Reservoir area, the same as that of the previous year.

3.6.1 Ecological environment of the farmland

The survey results showed that ecological environment in farmlands within the reservoir area in 2004 changed remarkably. With the impoundment of the reservoir reaching the height of 139 m and the adjustment of agricultural structure, the reservoir area quickened the pace to transform slope farmland and convert the arable land for forestry and grassland. The area of cultivated land and planting area of farm crops continued to diminish, and agricultural production kept its priority on grain crops but with lower proportion. In contrast, the percentage of commercial crops kept on rising.

In 2004, the total area of arable land in the reservoir area was 199,210 ha, 4.7% less than the previous year. The multiple cropping index was 238.0, 1.4 percentage points lower than that of the previous year. The total agricultural planting area was 502,900 ha, down by 5.4% compared with that of 2003. Among the total planting area, 359,200 ha were for grain crops and 143,710 ha for economic crops, taking up 71.4% and 28.6% of the total respectively. Compared with the previous year, the planting area of grain crops, mainly that of flatland in river valleys and cultivated land on mild slopes, continued on the decrease, whereas the areas of such economic forests as woodlands, orchards and tea gardens increased to some extent.

As to the farming system, paddy fields were dominated by two-crop system, accounting for 60.0% of the total, down by 1.3 percentage points than that of the previous year. Dry land mainly practiced the three-crop system, accounting for 56.0% of the total, 9 percentage points down compared with that of 2003.

3.6.2 Rural energy

In 2004, the energy structure in countryside of the Three Gorges Reservoir area was improved to some extent. Energies for rural households were still mainly derived from direct combustion of firewood and straw while the energy percentage from small hydropower stations and marsh gas generation kept on rising. Among all kinds of rural energy, straw constituted the largest proportion at around 39.5%, followed by firewood, small coal pits, small hydropower stations and marsh gas, accounting for 36.9%, 16.4%, 1.7% and 5.5% respectively. Compared with the previous year, energies derived from the direct combustion of stalks, small hydropower stations and marsh gas increased by 2.2, 0.5 and 2.1 percentage points respectively while those from direct combustion of firewood and small coal pits decreased by 3.7 and 1.1 percentage points.

In 2004, the development of marsh gas energy-generation and utilization in rural families of the reservoir area was accelerated. There were 1.357 million households using marsh gas energy in the area. 80,531 methane ponds were set up with annual capacity of 29.955 million m³ methane gas. The three figures were up by 25.1%, 4.9% and 3.5% respectively compared with that of 2003. The underlying reasons for rapid expansion of methane utilization were that the Central Government stepped up its efforts in eco-environmental improvement in the Three Gorges Reservoir area, especially in the development of eco-homes and extensive application and further popularization of high-efficiency eco-agricultural technologies based on marsh gas utilization.

3.6.3 Plant diseases and insect pests of crops

The total farmland area affected by plant diseases and insect pests in 2004 had a remarkable drop compared with that of 2003. The actual losses were alleviated, and the area involved in prevention and control of plant diseases and insect pests increased. There was no outbreak or great imperil of certain plant diseases or insect pests, and no new plant disease or insect pest was observed.

The total area suffering from plant diseases and insect pests was 699,130 ha·times, 426,610 ha·times of which were affected by insect pests mainly caused by paddy stem borer, and 272,510 ha·times by plant diseases dominated by Piricularia oryzae. In 2004, the total area affected by plant diseases and insect pests, the area subject to insect pests and that of plant diseases fell by 1.7, 1.5 and 1.9 percentage points respectively compared with that of 2003.

The area involved in the prevention and control of plant diseases and insect pests reached 598,610 ha·times, among them, 365,320 ha·times were for the prevention and control of insect pests and 233,290 ha·times for the prevention and control of plant diseases, an increase of 3.0% and 3.1% respectively in comparison with that of the previous year. The actual loss of grain production amounted to 40,064 tons, 0.7% less than the previous year, while 137,865 tons potential grain losses were averted, 0.8% higher than that of 2003.

Table 3-2 Statistics on the occurrences of major plant diseases and insect pests
in the Three Gorges Reservoir area

Types of plant diseases and insect pests	Area affected	Area for prevention and control	Control rate	Losses recovered	Actual losses	Degree
	(100 ha·times)	(100 ha·times)	(%)	(t)	(t)
Paddy stem borer	1143.9	938.2	82.02	28113	16161	Heavier than medium
Nilaparvata lugens	1585.3	1188.2	74.95	37899	833.8	Medium
Piricularia oryzae	251.7	396.4	157.47	30076	13294	Slight
Rice sheath blight	1454.6	1032.4	70.97	13244	599.1	Medium
Corn northern and southern leaf blight	29.6	3.9	13.06	29	234	Slight
Gibberella zeae	664.1	775.8	116.82	4335.7	614.9	Slight
Osmotin Harpinea	245.6	203.9	83.01	7841	4461	Slight
Corn sheath blight	420.8	395.4	93.96	7124	3283	Heavier than medium
Orange spider	1195.6	1052.6	88.04	9205.1	584.1	Medium

3.7 Geological Disasters

3.7.1 Earthquakes

In 2004, 1,062 earthquakes measuring at ML≥0.0 occurred from the head to the middle areas of the Three Gorges Reservoir area (108°20′-112°00′ E, 29°55′-31°45′ N). Among these earthquakes, 625 quakes measuring at 0.0≤ML＜0.9, 378 ones at 1.0≤ML＜1.9, 56 ones at 2.0≤ML＜2.9 and three at 3.0≤ML＜3.9. The largest earthquake, which measured at ML＝3.8, occurred in Yesanguan, Badong County (about 50 km away from the bank of the reservoir) at 11:14, September 13, 2004.

According to the results of GPS observation, crust deformation measurement and mobile gravity observation, there was obvious crust deformation response in the reservoir area after impoundment, and the regional tectonic stress field was undergoing adjustment. During 2004, micro-earthquake activities intensified in the Three Gorges Reservoir area, and eight earthquakes measuring over ML＝2.5 hit the region between Badong County and Zigui County.

Figure 3-3 Earthquake frequency from the head to middle of the Three Gorges Reservoir area in 2004

3.7.2 Collapses, landslides and mud-rock flows

● Monitoring and early warning

During 2004, professional monitoring of serious landslides and reservoir banks in 129 sites (sections) were conducted. A Grade III GPS monitoring network composed of 1,337 sites covering the whole reservoir area was established, and Local Area Networks (LAN) for 20 districts (counties) of the reservoir area were completed. Apart from the 1,216 landslide monitoring and preventing sites identified by phase II planning having finished the construction and put into operation, 1,939 other landslide monitoring and preventing sites identified in phase III planning were launched ahead of schedule, making the total number of such sites across the reservoir area to 3,155, which had greatly expanded the area where landslides could be prevented or monitored by the masses with enhanced capacity. As a result, a monitoring and early-warning system composed of a professional monitoring system, a mass monitoring and preventing system and an information system was initially established and played its due role. During 2004, 9 dangerous situations of landslides or collapses were predicted in the reservoir area of Hubei Province. 52 such dangerous situations were predicted in the reservoir area of Chongqing Municipality, which had effectively safeguarded the life and property of 9,757 people. At 2:00 am, June 14, 2004, Maliushu Slope in No. 9 production team, Xiushan Village, Nantuo Town of Fuling District glided towards the Yangtze River abruptly, sinking to a depth of 782 mm on average with horizontal move of 450 mm, causing the collapses of three houses and serious deformation of nine. Thanks to timely early warning and evacuation, the life of 45 local residents and properties amounting to 800,000 yuan were protected. On June 14, 2004, a new crack (with a length of 13.55m and a width of 2cm to 5cm) appeared in the landslide groups located in Group No. 3 and No. 4, Beishan Village, Zhonggulou neighborhood office in Wanzhou District. The adjacent packaging factory also saw a new crack (10m long and 2 cm to 3cm wide), and the slope was at a risk of collapse. However, the disaster prevention plan was initiated in time, and efforts were made to mitigate the danger, thus eliminating the potential threat to the lives and properties of 688 people.

● Prevention and control projects

Initiated in July 2001, the Geological Disaster Prevention and Control Project (phase II) of the Three Gorges Reservoir area lasted for two and a half years. By the end of 2003, all the tasks concerning prevention and control had completed according to plan. The project passed the initial check and acceptance by national authority in 2004.

During the second phase of this project, various prevention and control programs were completed including 158 collapse and landslide control programs (including 44 in Hubei Province and 114 in Chongqing Municipality), bank collapse control programs of 59 sections (22 in Hubei Province and 37 in Chongqing Municipality), 130 control programs on excavated high slopes (34 in Badong County, Hubei Province, 96 in Wushan County and Fengjie County of Chongqing Municipality), 803 deep-foundation treatment programs (178 in Badong County, Hubei Province and 625 in Wushan County and Fengjie County, Chongqing Municipality) as well as some resettlement projects.

The implementation of the Geological Disaster Prevention and Control Project (phase II) ensured the timely impoundment and power generation of the Three Gorges Reservoir, enhanced the geological safety of the resettlement area and improved the environment for human settlement in the reservoir area. After one year's water storage, the control projects basically realized its prevention and control objective and yielded remarkable social and economic benefits.