Browsing by Author "Mendoza, Romina"

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    Climate Change and Overuse: Water Resource Challenges during Economic Growth in Coquimbo, Chile
    (2022) Pizarro, Roberto; Garcia-Chevesich, Pablo A.; McCray, John E.; Sharp, Jonathan O.; Valdes-Pineda, Rodrigo; Sanguesa, Claudia; Jaque-Becerra, Dayana; Alvarez, Pablo; Norambuena, Sebastian; Ibanez, Alfredo; Vallejos, Carlos; Mendoza, Romina
    The arid Coquimbo region of Chile has experienced a significant economic growth in recent decades, fueled in large part by water-intensive activities such as mining and agriculture. Under this context, a monthly and annual trend analysis of precipitation, streamflow, and piezometric levels was carried out. Thus, 43 pluviometric stations, 11 fluviometric stations, and 11 wells were selected. These stations were evaluated for their temporal trends using the Mann-Kendall test. Results revealed a significant decrease in river flows, with negative and significant trends concentrated in the mean and maximum flows, both at annual and monthly levels. Likewise, positive trends were found in the depth to water table on wells, with significant trends in 81.8% of the monthly cases, and in 72.7% of the annual cases. While also decreasing over the same period, rainfall trends exhibit high variability and lacked significance. Although the amounts of precipitation have decreased, this does not seem to be the main factor responsible for the scarcity of water in the region, but rather an excessive consumption of this resource. This is endorsed by the increase in GDP (Gross Domestic Product), which is explained by activities that consume water (mining and agriculture). Similarly, an increase in the granting of underground water rights was verified, which speaks of the high demands for the resource. However, future modeling is advised to better understand the regional hydrology of the area and quantify the anthropic effects on water resources more precisely.
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    Establishment of Monterrey Pine (Pinus radiata) Plantations and Their Effects on Seasonal Sediment Yield in Central Chile
    (2023) Pizarro, Roberto; Garcia-Chevesich, Pablo; Ingram, Ben; Sanguesa, Claudia; Pino, Juan; Ibanez, Alfredo; Mendoza, Romina; Vallejos, Carlos; Perez, Felipe; Flores, Juan Pablo; Vera, Mauricio; Balocchi, Francisco; Bustamante-Ortega, Ramon; Martinez, Gisella
    Sediment production and transport in a basin are generally a function of the degree of soil protection, normally represented by plant cover. In this study, two basins located at similar latitudes but with different hydrological regimens and plant covers were studied, one with a pluvial regimen and forest plantations (Purapel) and another one with the pluvio-nival regimen and native forest (Nuble). For this purpose, sediment yield was analyzed in both drainage areas using the Mann-Kendall statistical test. Both basins showed larger amounts of sediment production during winter months. In addition, sediment yield trends did not show significant variation in the case of the Nuble, most likely due to non-relevant changes in plant cover over time. However, there is a sustained decrease in annual sediment release at Purapel, coinciding with the afforestation in the basin, so it is logical to attribute the referred reduction to this process. For the first time, the behavior of two watersheds is contrasted, one covered with native forest and the other one with forest plantations, appreciating that the basin covered with plantations presents a reduction in sediment production over time, which means that forest plantations are efficient in sediment retention, even in contrast to native forest. However, both basins have different types of soil, topography, etc., meaning that more studies are needed to support this theory.
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    Streamflow Trends in Central Chile
    (2023) Sanguesa, Claudia; Pizarro, Roberto; Ingram, Ben; Balocchi, Francisco; Garcia-Chevesich, Pablo; Pino, Juan; Ibanez, Alfredo; Vallejos, Carlos; Mendoza, Romina; Bernal, Alejandra; Valdes-Pineda, Rodrigo; Perez, Felipe
    The availability of water in Chile has shown signs of decline in recent decades. This is problematic because Chile's economy depends on mining, forestry, and agricultural activities, all limited by the availability of water resources. In this study, daily, monthly and annual flows in 31 basins located in the arid-semiarid zones (29 & DEG;12 & PRIME; S-33 & DEG;58 & PRIME; S) and in the humid-subhumid zones (34 & DEG;43 & PRIME; S-38 & DEG;30 & PRIME; S) of Chile were evaluated using the Mann-Kendall trend test and the quantile-Kendall procedure during three periods: 1984-2021 (31 stations), 1975-2021 (20 stations), and 1969-2021 (18 stations). Results showed that, at the annual level, trends were predominantly negative in both climatic zones and over the three periods analyzed. In the arid-semiarid zone, a higher frequency of annual significant negative trends was found in maximum flows in 1969-2021 and 1975-2021, compared to the last period under study. The humid-subhumid zone showed significant annual negative trends in all series analyzed. At the monthly level, on the other hand, the arid-semiarid zone showed a decrease in significant negative trends as the number of years analyzed increased, for all flow types. The humid-subhumid zone did not indicate a similar defined pattern. Likewise, the quantile-Kendall procedure showed a reduction in the significant trends as the length of the time series was increased in the arid-semiarid zone, but no such pattern was observed in the humid-subhumid zone. Furthermore, a relationship was observed for the PDO and the summer month flows for both zones. Consequently, it is concluded that the flow trends are generally negative, and their statistical significance depends on the period studied.