以“退耕还林”为主体的黄土丘陵区生态环境建设在过去10 年来取得了显著成效。为揭示“退耕还林”政策实施以来黄土丘陵区的降水与地表水和地下水的关系，本文以延安康沟流域为例，根据1997-2006 年延安站的逐日气象数据和康沟流域地表径流、泉水、井水水位实测水文数据，以及康沟流域地形地貌和土地利用等资料，利用相关分析法分析了康沟流域的降水、地表径流及地下水的时空变化特征，探讨了降水与地表水、地下水之间的关系，揭示了地表水和地下水对降水补给响应时间的差异性。分析结果表明：地表径流量与降水量有极好的季节响应关系，地表径流呈现为峰、谷交替曲线形态，降水少的年份出现单峰值，降水多的年份具有双峰值。降水量的多少和季节分配直接影响着井水、泉水的变化，同样降水条件下，井水的变化较泉水更敏感，泉水响应降水的时间大约滞后22~30 天，井水为7~10天。

The construction of eco-system in the loess hilly-gully region which was based on de-farming and afforestation policy has made remarkable improvement in the past decade. To probe into the relationship between precipitation and surface water and groundwater since the de-farming and afforestation policy was implemented, taking the Kanggou watershed in Yanan as an example, based on the daily meteorology data from Yan'an station during 1997-2006, and the actual measured data of runoff, spring flow, well level, landforms and land-use, this study was conducted by correlation analysis and GIS spatial analysis. This paper analysed the spatio-temporal variation of precipitation, surface water and groundwater in Kanggou watershed, explored the relationship between precipitation and surface runoff, and groundwater runoff, and revealed different responses to the precipitation of the surface water and the groundwater. Results are as follows: (1) There is a close connection between runoff and precipitation. The largest surface runoff occurs in the wet season with the peak precipitation. The distribution of precipitation and the surface water is basically consistent all the year. The runoff concentrates in May to September, accounting for 66.83% of the total annual runoff. The surface runoff forms a curve with peak and valley in turns, having a single peak with limited precipitation and double peaks with abundant precipitation. (2) There is a clear difference of surface runoff between morning and afternoon in the same day, and the difference between noon and afternoon is small. The average difference of surface runoff is 21.16 m³/d. The annual surface runoff varies significantly. One of the possible reasons is the difference of the wet year, normal year and dry year caused by the recharge of precipitation, and the other reason is the effects of eco-environment management in recent years. (3) The amount and the seasonal distribution of the precipitation directly affect the springs and wells, and wells are more sensible than springs under the same conditions. The response time of the wells to rainfall recharge is as long as 22 to 30 days, and the response time of springs is only 7 to 10 days. The reason is that groundwater runoff flow in rock gaps and soils is very slow. Also, the groundwater system contains giant storage vacuum, which makes permeation and discharge become limited. So the system relies on the concentrated or discontinuous recharge by precipitation as the only source of the storage, and then recharges to the other aquifers when seasons change.