12-9 Irrigation, Reservoirs, Flood Prevention, Water and Soil Conservation and Improvement of Saline-Alkaline Land
Item	1985	1990	1995	1996	1997
Number of Irrigation Areas (year-end)	5281	5363	5562	5608	5579
33 000 Hectares and Over	71	72	74	75	77
20 000-33 000 Hectares	66	76	99	108	115
Effective Irrigated Areas(10 000 hectares)	2077.7	2123.1	2249.9	2206.2	2249.5
33 000 Hectares and Over	599.6	604.7	631.4	615.0	640.8
20 000-33 000 Hectares	167.0	189.6	244.4	266.5	286.2
Number of Reservoirs	83219	83387	84775	84905	84837
Large	340	366	387	394	397
Medium-sized	2401	2499	2593	2618	2634
Small	80478	80522	81795	81893	81806
Capacity of Reservoirs(100 million cu.m)	4301	4660	4797	4571	4583
Large	3076	3397	3493	3260	3267
Medium-sized	661	690	719	724	729
Small	564	573	585	587	587
Total Area Liable to Flooding or Water-logging (10 000 hectares)	2420.7	2446.7	2442.5	2458.2	2458.2
Flooded or Waterlogged Area Under Control (10 000 hectares)	1858.4	1933.7	2006.5	2027.9	2052.6
Percentage to Total Area Liable to Flooding or Water logging	76.8	79.0	82.2	82.5	83.5
Total Area of Soil Erosion(10 000 hectares)	12920	13600	16300	18266.4	18266.4
Area of Soil Erosion Under Control(10 000 hectares)	4640	5300	6690	6932.1	7224.2
Percentage to Total Area of Soil Erosion	35.9	39.0	41.0	38.0	39.5
Total Area of Saline-Alkaline Land(10 000 hectares)	769.3	753.9	765.6	772.5	772.5
Improved Area of Saline-Alkaline Land(10 000 hectares)	456.9	499.5	543.4	551.3	561.2
Percentage to Total Area of Saline-Alkaline Land	59.4	66.3	71.0	71.4	72.6
Total Length of Dikes (10 000 km)	17.7	22.0	24.7	24.8	25.1
Area of Land Protected by Dikes(10 000 hectares)	3106.0	3200.0	3060.9	3268.6	3414.6

a) The capacity of the large reservoirs is over 100 million cu.m, while that of the medium ones is from 10million to 100 million cu.m,and that of the samll ones is from 100 000 to 10 million cu.m.