5.3 Capture of Spring Discharge

Spring discharge is in part a function of local and regional hydraulic gradients. The spring elevation is fixed, but the distal heads can decline due to pumping, which reduces the head gradient towards the spring. This will reduce the flow towards the spring, which reduces its discharge – exactly the same mechanism that causes streamflow depletion. This effect has been observed in long‑term discharge measurements at regional springs in southern Nevada, USA (Figure 14), for example, as well as in springs in North Africa (Margat et al., 2006). It is not uncommon for springs to go dry because of groundwater development in the spring’s source area. But dry springs can recover. Manse Spring (shown in Figure 14), having gone essentially dry in 1977 (although small intermittent winter flows were reported after that), started to flow again in the late 1990s (San Juan et al., 2010). The recovery of spring flow was in response to reduced pumping and rising groundwater levels since 1980, and discharge was reported to be about 1.9×106 m3/yr in 2011 (Halford and Jackson, 2020).

Graph showing annual discharge from regional springs in Pahrump Valley, Nevada, 1875-1978
Figure 14 – Annual discharge from regional springs in Pahrump Valley, Nevada, 1875-1978, showing trend of decreasing spring flow after onset of pumping (modified from San Juan et al., 2010).


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