It is necessery that the total consumptive use of water in the rotation period is equal to the total effective precipitation(pre- cipitation minus runoff depth)in the loess hilly region.
在黄土丘陵区要求林草与农作物地在轮作周期内的总耗水量与有效雨量（降雨量与径流深之差）持平。
2
The effects of high temperature pre-precipitation on the stress corrosion properties of the heat affected zone were also studied after welding.