Hello,
Please i want to know the transmissivity/sustainable yield values and how these values correlate with the suitability of an aquifer. i will be glad to also know how these values will aid in selecting the water use for the well.
Transmissivity of an aquifer is a function of its hydraulic properties such as porosity, texture, permeability and hydraulic conductivity. These hydraulic properties determines the yield of an aquifer at any given time and location.
It is very well known that higher the transmissivity, higher will be the yield from an aquifer. The yield from an aquifer varies from place to place or region to region. Classification of aquifers as high yielding or low yielding is purely qualitative. In a given area, depending on the water scarcity and well yield, the aquifers are classified based on their yield. An aquifer with certain yield property is considered low yielding in one place but the same may be considered as an potential aquifer in another place/region, in the absence of any alternate source. Hence the local hydrogeologist is the best judge to classify the aquifers based on the yield and their suitability for various purposes.
I second all the comments made by N B Narasimha Prasad but add the following for detail.
Transmissivity is the amount of water that can be extracted from an aquifer and is often expressed as m2/day. It is defined by the following equation T = K*b, where T is transmissivity, K is hydraulic conductivity (m/day) and b is depth of your aquifer (m). As a rule of thumb transmissivities I have been told by word of mouth that 0.015 m2/sec are considered suitable aquifers for exploitation but I don't have a reference for this.
In terms of sustainable yield this depends on the rate of extraction. For example a small hand pump used by one family might be able to be suitable in a relatively lower T area whilst industrial pumping for mass water extraction would require a greater T.
For analysing sustainability fully you should also be looking to see how specific storage, specific yield and sediment compressibility all affect this. One problem of over extraction is ground subsidence (e.g. Motagh et al. (2008) Geophysics Research Letters, 35, L16403).
If you want a really good overview of the topic I would recommend reading Domenico and Schwartz (1990 or later edition's)'s text book on hydrogeology for a more in depth analysis of the topic.
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