INTERNATIONAL STUDENT RESEARCH EXPERIENCE: THE EFFECTS OF EVAPOTRANSPIRATION ON RIVER WATER CHEMISTRY IN THE OKAVANGO DELTA, NORTHWEST BOTSWANA
The objective of our trip was to jointly conduct research in the Okavango Delta with peers from the University of Botswana. The Okavango Delta, an oasis in the Kalahari Desert, is located on the world’s largest alluvial fan, covering 22,000 Km2. The aim of our research was to measure water properties throughout the delta, while learning how to manage both cultural differences as well as logistical barriers involved with conducting international research.
The Okavango River originates in Angola and discharge in the delta is affected by a seasonal flooding pulse. Due to the slow nature of water transit in the low relief area, water in the southerly distal ends is subject to more evaporation and, therefore, must have different chemical properties. In order to observe short-term changes, we conducted diel investigations, sampling and measuring water properties at thirty minute and one hour intervals. The parameters included photosynthetically available radiation, water level, temperature, total dissolved solids, pH, dissolved oxygen, major ions, silica, alkalinity and dissolved inorganic carbon. During the day, transpiration and evaporation raises the concentration of dissolved solutes and at night, due to the lack of sunlight, river levels rise, lowering concentrations of dissolved solutes. Our results showed pronounced variations in water properties that corresponded to both day and night. For example, daytime shows higher temperatures, lower water levels and increased concentrations of dissolved solute. This suggests a strong influence of evapotranspiration on river water properties and an important role of vegetation in river water chemistry.
Collecting measurements in a regimented manner required a great deal of teamwork and cooperation. Dependence on one another’s skills and work ethic was critical to the team’s success. Logistical issues of all sorts required that each team member collaborate in order to achieve our desired outcomes. In today’s ever-expanding global society, international research is becoming increasingly prevalent and adaptive skills will prove valuable in the evolving world of geology.