Changes in the surface water hydrologic characteristics of an endoreic basin of northern Mexico from 1970 to 1998

Abstract

Abstract:The western Sierra Madre is the main water-providing area of northern Mexico. However, most of this mountain range has suffered a progressive degradation of soils and vegetation due to overgrazing and deforestation, for four or five decades. The objective of this study is to determine the impacts of these changes on water balance and hydrodynamic basin behaviour.The hydrological data of two basins (the Sextin basin, 4660 km 2 and the Ramos basin, 7130 km 2 ) of this area were analysed. Annual runoff coefficients have not changed. Therefore, other indices were used to determine changes in the streamflow regime:ž an index of irregularity of daily discharge; ž the separation of flood flow and base flow; ž the lag time of the watersheds; ž the baseflow recession index; ž the two-day recession index. Some changes were noticeable at the basin scale in the water balance of the catchments: ž the ratio of the flood runoff coefficient to the base runoff coefficient increased from the 1970s to the 1990s; ž the basin lag time decreased 2Ð1% in the Ramos basin and 6Ð1% in the Sextin basin; ž the two-day recession index and the baseflow recession index increased, reflecting a more rapid decrease of streamflow after the peak flow; ž the mean annual runoff coefficient and the irregularity as estimated by the index used here showed no significant evolution.The convergence of such observations confirms that dramatic changes in the evolution of water resources in the near future in this area are to be expected, if the current land use is not strongly modified. Water management and dam operation would also be seriously affected.

Hydroclimatology of the North American Monsoon region in northwest Mexico

“…This study fills a niche in previous research in this region that has predominantly focused on smaller basin-scale processes (e.g. Descroix et al, 2002a,b;Viramontes and Descroix, 2003), globalscale analyses (e.g. Dettinger and Diaz, 2000) or the inter-annual variability of streamflow and precipiation Brtio-Castillo et al (2002;.…”

“…With the exception of the limited study by Viramontes and Descroix (2003), the specific mechanisms for generating runoff from the SMO (e.g. infiltration excess, saturation excess or groundwater discharge) have yet to be clearly diagnosed.…”

“…Additionally, Viramontes and Descroix (2003), analyzing the changing character of hydrograph response from two catchments along the eastern flank of the SMO, found that significant alterations in landscape characteristics are currently impacting runoff genesis. Specifically, basin lag times, streamflow contributions from baseflow, and flood hydrograph recession times all decreased from the 1970s to the 1990s.…”

Change in Sahelian Rivers hydrograph: The case of recent red floods of the Niger River in the Niamey region

“…In endorheic basins of Northern Mexico, deforestation and overgrazing did not lead to an increase in runoff but to a decrease in lag time and in base flow volume and duration, as well as to an enhancement and a widening of river beds (Viramontes and Descroix, 2003); this already led the authors to investigate the boundaries between Hortonian and Hewlettian processes . This runoff increase process can be reversed at least for temperate climates: in northern Mediterranean areas in Europe, rural abandonment led to a progressive afforestation since the end of the 19th century.…”

New species and records of Ulmeritoides (Ephemeroptera: Leptophlebiidae) from Costa Rica

“…semi-arid climates (Viramontes andDescroix 2003, Bewket andSterk 2005). In stream environments of decreasing permanence in northwestern Costa Rica, an ancestor of the U. guanacaste complex could have responded with a shortened life cycle.…”