Browsing by Author "Valdes-Pineda, Rodrigo"

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    A Rainfall Intensity Data Rescue Initiative for Central Chile Utilizing a Pluviograph Strip Charts Reader (PSCR)
    (2020) Pizarro-Tapia, Roberto; Gonzalez-Leiva, Fernando; Valdes-Pineda, Rodrigo; Ingram, Ben; Sanguesa, Claudia; Vallejos, Carlos
    To develop intensity-duration-frequency (IDF) curves, it is necessary to calculate annual maximum rainfall intensities for different durations. Traditionally, these intensities have been calculated from the analysis of traces recorded by rain gauges on pluviograph strip charts (PSCs). For many years, these charts have been recorded and analyzed by the personnel who operate and maintain the pluviograph gauges, thus the reliability of the observational analysis depends exclusively on the professional experience of the person performing the analysis. Traditionally, the analyzed PSCs are physically stored in data repository centers. After storing rainfall data on aging paper for many years, the risk of losing rainfall records is very high. Therefore, the conversion of PSC records to digital format is crucial to preserve and improve the historical instrumental data base of these records. We conducted the first "Data Rescue Initiative" (DRI) for central Chile using a pluviograph strip charts reader (PSCR), a tool that uses a scanner-type device combined with digital image processing techniques to estimate maximum rainfall intensities for different durations for each paper band (>80,000 paper bands). On the paper bands, common irregularities associated with excess ink, annotations, or blemishes can affect the scanning process; this system was designed with a semi-automatic module that allows users to edit the detected trace to improve the recognition of the data from each PSC. The PSCR's semi-automatic characteristics were designed to read many PSCs in a short period of time. The tool also allows for the calculation of rainfall intensities in durations ranging between 15 min to 1 h. This capability improves the value of the data for water infrastructure design, since intense storms of shorter duration often have greater impacts than longer but less intense storms. In this study, the validation of the PSCR against records obtained from observational analysis showed no significant differences between maximum rainfall intensities for durations of 1 h, 6 h, and 24 h.
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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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    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.
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    The Impact of a Lack of Government Strategies for Sustainable Water Management and Land Use Planning on the Hydrology of Water Bodies: Lessons Learned from the Disappearance of the Aculeo Lagoon in Central Chile
    (2022) Valdes-Pineda, Rodrigo; Garcia-Chevesich, Pablo A.; Alaniz, Alberto J.; Venegas-Quinones, Hector L.; Valdes, Juan B.; Pizarro, Roberto
    Several studies have focused on why the Aculeo Lagoon in central Chile disappeared, with a recent one concluding that a lack of precipitation was the main cause, bringing tremendous political consequences as it supported the argument that the government is not responsible for this environmental, economic, and social disaster. In this study, we evaluated in detail the socio-economic history of the watershed, the past climate and its effects on the lagoon's water levels (including precipitation recycling effects), anthropogenic modifications to the lagoon's water balance, the evolution of water rights and demands, and inaccurate estimates of sustainable groundwater extraction volumes from regional aquifers. This analysis has revealed novel and undisputable evidence that this natural body of water disappeared primarily because of anthropogenic factors (mostly river deviations and aquifer pumping) that, combined with the effects of less than a decade with below-normal precipitation, had a severe impact on this natural lagoon-aquifer system.
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    The Large-Scale Effect of Forest Cover on Long-Term Streamflow Variations in Mediterranean Catchments of Central Chile
    (2022) Pizarro, Roberto; Valdes-Pineda, Rodrigo; Garcia-Chevesich, Pablo A.; Ibanez, Alfredo; Pino, Juan; Scott, David F.; Neary, Daniel G.; McCray, John E.; Castillo, Miguel; Ubilla, Patricio
    Forest ecosystems play an important role in hydrological processes as surface and subsurface runoff, as well as the storage of water at the catchment scale. Therefore, it is important to have a greater understanding of the effects of forests in the long-term water balance of Mediterranean catchments. In this sense, this study evaluates the effect of native forests, forest plantations, and the combination of both, on long-term streamflow variations in central Chile, an unusual area of Mediterranean climate characterized by a well-marked annual cycle with dry summers and wet winters. Thus, the temporal pattern of monthly streamflow was evaluated for mean flow (Qmean), maximum flow (Qmax), and minimum flow (Qmin) in 42 large-scale (>200 km(2)) Mediterranean catchments. Each series of monthly streamflow data was QA/QC, and then evaluated using the Mann-Kendall's non-parametric statistical test to detect temporal variations between 1994 and 2015. In addition to the previous analysis, the monthly series were grouped into wet seasons (April-September) and dry seasons (October-April), to determine if there were any significant differences within the annual hydrological cycle. The areas covered with native and forest plantations and their relative changes were evaluated for each catchment through streamflow variations and forest cover indicators. Results revealed that streamflow variations are positive and significant when more forest cover exists. The intra-catchment relationships assessed for both species revealed the significant role of native forests and mixed masses as key ecosystems for the long-term conservation of summer streamflow in Mediterranean catchments of central Chile. These findings encourage an urgent need to create highland afforestation programs on degraded areas of central Chile, to maximize water storage in a region that is quickly drying out due to unsustainable water and land use management practices and the effects of global warming.