13-10  Irrigation, Reservoirs, Flood Prevention, Waterand Soil Conservation and Improvement of Saline-Alkaline Land
Item		1990	1995	2000	2002	2003	2004
Number of Irrigation Areas at the year-end(set)		5363	5562	5683	5691	5729	5800
33 000  Hectares and Over		72	74	101	110	112	111
20 000-33 000  Hectares		76	99	141	168	169	169
Effective Irrigated Areas	(10 000 hectares)	2123.1	2249.9	2449.3	2503.0	2524.4	2550.6
33 000  Hectares and Over		604.7	631.4	788.3	915.8	938.1	971.4
20 000-33 000  Hectares		189.6	244.4	344.0	407.2	408.4	405.7
Number of Reservoirs		83387	84775	85120	85288	85153	85160
Large		366	387	420	445	453	460
Medium-sized		2499	2593	2704	2781	2827	2869
Small		80522	81795	81996	82062	81873	81831
Capacity of Reservoirs	(100 million cu.m)	4660	4797	5184	5595	5658	5542
Large		3397	3493	3842	4229	4278	4147
Medium-sized		690	719	746	767	783	796
Small		573	585	594	597	597	599
Water-saving Irrigated Area  (10 000 hectares)				1638.9	1862.7	1944.3	2034.6
Flooded or Waterlogged Area(10 000 hectares)		1933.7	2006.5	2098.9	2109.7	2113.9	2119.8
Area of Soil Erosion under Control		5300	6690	8096	8541	8971	9200
	(10 000 hectares)
Improved Area of Saline-Alkaline Land		499.5	543.4	584.1	528.3	586.5	596.2
	(10 000 hectares)
Total Length of Dikes	(10 000 km)	22.0	24.7	27.0	27.4	27.8	27.7
Area of Land Protected by Dikes		3200.0	3060.9	3960.0	4286.2	4387.5	4393.4
	(10 000 hectares)
a) The capacity of the large reservoirs is over 100 million cubic meters, while that of the medium ones is from 10 million to 100 million cubic meters,
and that of the small ones is from 100 000 to 10 million cubic meters.