Method for the hydro climatological characterization and hydrologic assessment of the natural watersheds in the mining area in the central Cesar State, Colombia. Mean, maximum and minimum flows

Alfonso Rodriguez, Ricardo Aguilar, German Acero, German Santos, Romeo Ramos

Wednesday 1 july 2015

9:15 - 9:30h at Central America (level 0)

Themes: (T) Water resources and hydro informatics (WRHI), (ST) Catchment hydrology

Parallel session: 8H. Water resources - Catchment

A methodology was developed to evaluate the superficial water availability based on the requirements established by Drummond Ltd, which is in charge of the surface mining exploitation in the south of the State of Cesar, Colombia. The methodology includes a long term Water Balance to estimate the mean flow in any point of the watershed drainage network and the determination of the maximum flow, for a given return period, in previously defined points. The technique developed to estimate the different kinds of flows is supported by a GIS and commercial as well as public domain software. In addition, new tools were developed to evaluate hydrological processes that can be used in any other watershed system. The first research phase deals with the superficial water availability for the natural conditions. The region under study has an area of more than 4000 km2 and 13 mayor watersheds were defined. In the next phases, several particular studies were made to evaluate the water availability according to the transformations occurred. The GIS implemented and structured has a spatial model that covers the entire drainage network in natural conditions a series of hydro climatological variables in a spatial extend to the watershed divide in the Sierra del Perija in The East Andes. The model includes, based on 24 hours maximum rainfall depth, a methodology to generate rainfall and construct hyetographs. It is possible to classify the soils according to the US Soil Conservation Service methodology to obtain the required Curve Numbers in the rainfall- runoff transform process. To estimate the mean flow a long term water budget balance was performed using the ArcGis- Esri spatial analyst tool in each cell for the entire study zone based on the mean precipitation an evaporation grids. The developed methodology allows perform analysis and obtain results for the extreme flows and hydrographs in any point of a channel in the mining exploitation zone. The maximum flows are estimated by the HEC-HMS model based on the precipitation data and the physical characteristics previously obtained and available in the GIS and processed by HEC-GeoHMS. The channel routing is made hydrological by the Muskingum method. In conclusion, a model was developed that reproduce the natural conditions and to support decisions about the water management in the mining exploitation