|
|
Robati, A., & Barani, G. A. (2009). Modeling of water surface profile in subterranean channel by differential quadrature method (DQM). Applied Mathematical Modelling, 33(3), 1295–1305.
Abstract: This study, investigates the hydraulic of flow in a subterranean channel headspring. The continuity and momentum equations of flow in porous media considering real conditions were used and the basic equation of flow in a subterranean channel was resulted. This equation is very similar to the spatially varied flow with increasing discharge. An equation, defining the hydraulic parameters of a subterranean channel section was adopted. Then differential quadrature method (DQM), was applied to the equation of flow in subterranean channel, consequently the water surface profile was resulted. To illustrate the rightness of model, the hydraulic parameters of flow in the Gavgard branch of the Joopar Goharriz Qanat were measured and the water surface profile was determined. This water surface profile was compared to the water surface profile computed by the model, which are in good agreement.
|
|
|
|
Klock, H., Külls, C., & Udluft, P. (2000). Estimation of relative recharge values for the northern Kalahari catchment, Namibia. Journal of African Earth Sciences, 30(4), 47–48.
|
|
|
|
Schwiede, M., Duijnisveld, W. H. M., & Böttcher, J. (2005). Investigation of processes leading to nitrate enrichment in soils in the Kalahari Region, Botswana. Physics and Chemistry of the Earth, Parts A/B/C, 30(11), 712–716.
Abstract: In Southern Africa elevated nitrate concentrations are observed in mostly uninhabited semi-arid areas. In the Kalahari of Botswana groundwater locally exhibits concentrations up to 600mg/l. It is assumed, that nitrate found in the groundwater originates mainly from nitrogen input and transformations in the soils. Our investigations in the Kalahari between Serowe and Orapa show that cattle raising is an important source for enhanced nitrate concentrations in the soils (Arenosols). But also in termite mounds very high nitrate stocks were found, and under natural vegetation (acacia trees and shrubs) nitrate concentrations were mostly unexpectedly high. This nitrate enrichment in the soils poses a serious threat to the groundwater quality. However, calculated soil water age distributions in the unsaturated zone clearly show that today’s nitrate pollution of the groundwater below the investigation area could originate from natural sources, but cannot be caused by the current land use for cattle raising.
|
|
|
|
Lightfoot, D. R. (1996). Moroccan khettara: Traditional irrigation and progressive desiccation. Geoforum, 27(2), 261–273.
Abstract: A 300 km network of khettara (qanat) subsurface irrigation channels was excavated in the Tafilalt basin beginning in the late 14th century. More than 75 of these chains provided perennial water following the breakup of the ancient city of Sijilmassa. Khettara continued to function for much of the northern oasis until the early 1970s, when new technologies and government policies forced changes. Data on origins, maintenance, and current use were collected from archival sources, aerial photographs, Landsat imagery, and from interviews. Insufficient water resources and unsustainable practices have dramatically lowered the water table, drying up khettara. This has resulted in a loss of local control over water resources, abandonment of a sustainable irrigation system, and progressive desiccation.
|
|
|
|
Wolfe, P. (1959). The Simplex Method For Quadratic Programming. Econometrica, 27, 170.
|
|
