布朗大学同位素地球化学Hydrogenandoxygenisotopesingroundwater

1、Fine grained soils = 3 to 5 mFractured rock (fast infiltration) 10 m Isotopic changes in confined aquifer signifies mixing of different recharge watersEnriched precipitationEvaporative enrichment in summer runoffVery low slope!Displacement Recharge )/(arg3shift )/(arg22shift 18yrmmerechOyrmmerechD%5

2、65. 0D n evaporatio %gwNileDSalt buildup mainly due to agricultural practice, which has to be changed to stop the soil salinity increasesSalinity goes up, little change in DH II mainly recharged from IIIer River, but has strong seasonal contribution from Weihung RiverOld GW, before DamNew GW, After

3、damSource water of NileTotal stream discharge = Storm flow + GroundwaterrgwrttgwQQrgwrssrttgwgwrgwssgwttrSiSiSiSiQSiSiQQQQQ)()()()(It is pre-event groundwater, not storm water that contributes the greater amount to stream flow during precipitation events (except urban rainfall)Phase I: Simple mixing

4、 between pre-storm base flow (BF) and rain falling on the channel Phase II: Increasing influence of direct runoff which has 18O of rain, but higher E.C. due to flow over the ground from some distance from the channelPhase III: Decrease in the direct runoff/baseflow ratio and establishment of a new base flow, which includes the influence of the storm rechargeCl- separation show lower runoff contribution, which is explained due to accumulation o