Erosion rates and geomorphological indices in three coastal basins in the south of the Baja California peninsula, Mexico [Tasas de erosión e índices geomorfológicos en tres cuencas costeras al sur de la península de Baja California, México]
Lozano J.O.N.,Comision Nacional del Agua Conagua |
Sanchez E.N.,Instituto Polytechnic Nacional |
Zamudio J.L.C.,Autonomous University of the State of Hidalgo
Boletin de la Sociedad Geologica Mexicana | Year: 2012
Coastal drainage basins in the southern part of the peninsula of Baja California are an important part for the stability of the littoral cell system of the coast in Baja California, because they are the major sediment sources. Migriño, El Salto and El Tule watersheds are vulnerable to erosion due to the steep slopes and geographic location because in this part of the peninsula rainfall associated with summer hurricanes has a mayor influence. Using the RUSLE equation (Revised Universal Soil Loss Equation) and geomorphologic indexes, obtained by GIS techniques, we assessed the spatial distribution of erosion rates and its relationship to lithology, geomorphic features, soil distribution and structural patterns. This allowed us to know the control that soil distribution and geomorphic features exert on the distribution of erosion rates within each drainage basin. Moderate (0.1 to 0.5 Mg ha-1 year-1) to high (0.5 to 2 Mg ha-1 year-1) erosion rates are associated to slopes equal to or greater than 15°(mountain slopes), and Litosol-Regosol types; low erosion rates (0 - 0.1 Mg ha-1 year-1) are associated to slopes of less than 5°(gentle hill slopes and plains), and Regosol types. Analyses of geomorphologic indexes show that river drainage basins are young, and are associated to moderate or negligible neotectonic activity, as evidenced primarily by structural control in the upper basin. Changes in geomorphologic indexes in the middle and lower basins, where erosion and depositional processes are occurring, indicate little structural control.
Arreguin-Cortes F.,Comision Nacional del Agua Conagua |
Lopez-Perez M.,Comision Nacional del Agua Conagua |
Velazquez-Mireles C.,Comision Nacional del Agua Conagua |
Lopez-Corzo R.,Comision Nacional del Agua Conagua
Tecnologia y Ciencias del Agua | Year: 2013
This study presents an analysis of drought in the basins of the Colorado and Bravo Rivers using the Streamflow Drought Index, SDL For the Colorado River, three years of extreme drought (1934, 1977 and 2002) were recorded in the entire basin and its upper region, and four years (1928, 1929, 1935, and 1936) in the lower basin. Applying this same approach to the Bravo River, extreme drought was recorded for the K3 period (October-June) period during the agricultural year of 1901-1902. The Standardized Precipitation Index, SPI, was only applied in the Colorado River basin, where extreme drought was found in both the lower and the entire basin for the years 1950, 1956 and 1989. In addition, extreme drought also occurred in the upper basin during the latter year. These results are important to joint water management by Mexico and the United States in both basins in order to meet the demands of their inhabitants, fulfilling the promises established in the 1944 International Water Treaty and taking the measures needed concerning the impact of climate change on the hydrological cycle in the region.