Generalized Drought Risk Assessment And Its Coping Strategies

Drought is the extreme event in water cycle. With the increasing impact of climatechange and human activities, drought happens in more area with higher frequency, andnow it endangers the water and ecology security in river basin. The occurrences of droughtevents usually contain dual characteristics: determinacy and randomness. A risk modelbased on "natural-artificial" dualistic water cycle theory should be taken to cope with thisproblem.From the perspective of the water resources system, this article proposed aconnotation and a quantitative evaluation method to generalized drought. The drivingfactors of natural climate variability (NCV), anthropogenic climate change (ACC),underlying conditions change (UCC) and hydraulic engineering regulation (HER) can alterthe impacts of drought events. The unitary driver model of generalized drought evolutionwas built. After combining the dual characteristics of drought events, the methods ofgeneralized drought risk assessment and generalized drought risk division were proposedbased on3S technology. Some measures were put forward to cope with generalizeddrought risk, and their effects were evaluated. Based on the above theories andtechnologies, Dongliao River Basin with high frequency of drought events was taken foran example.According to the identification of the driving mechanism of generalized drought inDongliao River Basin, it could be seen that the generalized drought was affected by NCVand HER during1960to1981, and affected by NCV, ACC and HER during1982to2010.The results simulated by generalized drought assessment index were comparativelyunanimous to the drought disasters happened in Lishu and Gongzhuling of Dongliao RiverBasin actually. The results simulated by the generalized drought assessment index werebetter than that of Standard Precipitations Index, Palmer Drought Severe Index and Rate ofWater Deficit Index. The generalized drought frequency, duration and severity differwidely between assessment units in Dongliao River Basin from1960to2010. They werealso different in different years, and their centers of gravity transferred obviously in thespace.The risk values of the assessment units of Jinman Reservoir, Bayi Reservoir, YishanReservoir, Anxi Reservoir, Sanliang Reservoir, Nanwaizi Irrigated Area, Qintun IrrigatedArea, Lishu Irrigated Area and Shuangshan Irrigated Area were higher than other assessment units. The areas with high risk were decreased, and the areas with low riskwere increased by the impacts of ACC, UCC and HER.Some response strategies of enhancing the coefficient of farmland irrigating water use,decreasing the soil evaporation and implementing inter-basin water transfer project wereproposed to cope with generalized drought in Dongliao River Basin. The risk values ofsome assessment units were decreased, and some assessment units were increased byenhancing the coefficient of farmland irrigating water use. Nearly all assessmentunits risk values were reduced by decreasing the soil evaporation. The risk values of theassessment units of reservoirs were decreased by implementing interbasin water transferproject.Based on this research, both theories and technologies to cope with the droughtproblems in changing environment will be further developed, and provide scientific basisto deal with drought problem in Dongliao River Basin in the meantime.