Dear Scholars,
I am working on water level dynamics of semi-closed basins (marginal grabens) under fast agricultural development. There is a scarce of hydrological data in our study area. Thus, representative observational wells, shallow lakes, springs and river baseflow were selected to monitor water levels over the last two years. Can monitoring water level at these water points capture the water level dynamics in the marginal grabens?
With best regards,
Hailemariam
I am not famiar with Graben hydrology, but hydrology with parallel faults and land use change are apt to be more complex than normal hydrology. The hydrology of graben may be also interconnected with adjacent areas not adjusted to fault. You have the right idea in collecting data from various water sources, and helpful to have raingauge network. Enough data to conduct basic water balance where data or estimates collected for P = R + ET + changes in soil moisture and groundwater storage would help. If there may be springflow coming from adjacent or outside areas, or loss of flow into fault zones, these can create some substantial anomolies in the flow records that may be hard to characterize. I would sugggest that capturing hydrological dynamics within areas affected by geological abnormalities as well as land use changes associated with some development can be challenging, so if you find abnormalities, they may lead to the need for added measurement points. Two years data is seldom enough, so if you have any nearby long term stream gauging and rainfall recording stations, those may help evaluate and classify if the records are within the norm or outside. Discussing your approach with
But someone has to take these measures in winter and summer, and for at least 20 years, because it has been seen that watershed, it is not enough to study them in a period of 10 years.
Even if the monitoring stations are outside the study area, the data so collected can be extrapolated to your study area. However, the area so selected should be comparable in every respect, such as geology, geomorphology, hydrology, etc., to the study area. Coming to your prime objective of monitoring groundwater dynamics, I think you will be measuring the discharge from the springs and the base flow in rivers and then relate it to the groundwater level fluctuations in the study area. You may note that the monitoring should be done during different seasons, such as rainy, summer and winter and it should be for a minimum period of 5 years, two years is too short.
Dears: William, Marcelo & Narasimha Prasad,
Your suggestions are of paramount important for me.
I thank you so much.
With best regards,
Hailemariam
Taking the cognisance of above mentioned suggestions, I would like to add that the monitoring of groundwater level should also be representative in both parts of graben (faulted structure) then only we may interpret/explain the groundwater regime and its dynamics.
The water levels measured in lakes and springs may not represent the true value of piezometric head of the subsurface aquifer. You need to install piezometers. In stream beds and, if possible, in the lakes. Such investigations in glacial lakes in Canada identified deep aquifers.
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