Groundwater responses to controlled water releases in the limitrophe region of the Colorado River: Implications for management and restoration

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• 作者：Jorge Ram¨ªrez-Hern¨¢ndez ; Osvel Hinojosa-Huerta ; Mauricio Peregrina-Llanes ; Alej ; ra Calvo-Fonseca ; Edgar Carrera-Villa
• 关键词：Groundwater&ndash ; surface water interactions ; Flow regulation ; Colorado River delta ; Riparian restoration ; Colorado River limitrophe region
• 刊名：Ecological Engineering
• 出版年：2013
• 出版时间：October, 2013
• 年：2013
• 卷：59
• 期：Complete
• 页码：93-103
• 全文大小：2627 K

文摘

Flow regulation and water diversion for irrigation have considerably affected the exchange of surface water between the Colorado River and its floodplains. However, the way in which both have impacted groundwater-surface water interactions is not completely understood. The objective of this study was to conduct a hydrologic analysis of the 2009-2010 winter flows released into the limitrophe region of the Colorado River in order to characterize the surface flows along this dry reach and, for the first time, study the impact of winter flows on the groundwater conditions in the area. The study used existing data on groundwater levels that was collected from regional piezometers on both sides of the limitrophe every five years from 1980 to 2005. Regional flow direction from NE to SW was observed in all years. A groundwater depression cone in the southwest part of the limitrophe was identified from 1980 to 1995. A general rise of groundwater levels was observed from 2000 to 2005 on both sides of the limitrophe, but during the same time period, a depression cone formed along the border between Arizona and Sonora, in the Mesa Arenosa on the Mexican side of the border. In order to identify the water table evolution within the limitrophe riparian zone, nine sets of piezometers were constructed in an arrangement perpendicular to the main river channel. Water table levels were measured automatically every 30 min and were also manually measured periodically. Nine geohydrological cross sections were constructed using the topographic relief from LIDAR elevation points and depth to groundwater measurements during water discharges in the Colorado River channel at Morelos dam. Groundwater seepage from irrigation canals, irrigation returns, and river discharge flows were identified and the depth to groundwater and its influence on riparian vegetation was analyzed. A strong correlation between flow discharge (up to 60.49 hm³ from November 2009 to April 2010) and groundwater elevation (average elevation change of 1.62 m on January 22, 2010) in time and space was found. The percentage of water retained in the main river channel decreased from 100 % in the first discharge event (December 12-13, 2009) to 36 % after the last discharge event (April 9-17, 2010), due to remaining moisture in the unsaturated soil. The total volume of water retained, infiltrated, and evaporated, was 60 % (36.6 ¡Á 10⁶ m³) of the total water discharged. The delay time of the groundwater front during a discharge event was on average 6:30, 20:06, and 28:53 h from section 1 to section 2, 1-3, and 1-4 respectively. This historical study provides insight into how floods affect the groundwater system, which is the foundation for aquatic and riparian biodiversity. This issue is of increasing relevance given growing international interest in rehabilitating the riparian and aquatic ecosystems of the Colorado River delta through intentional flood releases.