Browsing by Author "Ingram, Ben"

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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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    Comparing Methods for the Regionalization of Intensity-Duration-Frequency (IDF) Curve Parameters in Sparsely-Gauged and Ungauged Areas of Central Chile
    (2023) Sanguesa, Claudia; Pizarro, Roberto; Ingram, Ben; Ibanez, Alfredo; Rivera, Diego; Garcia-Chevesich, Pablo; Pino, Juan; Perez, Felipe; Balocchi, Francisco; Pena, Francisco
    Estimating intensity-duration-frequency (IDF) curves requires local historical information of precipitation intensity. When such information is unavailable, as in areas without rain gauges, it is necessary to consider other methods to estimate curve parameters. In this study, three methods were explored to estimate IDF curves in ungauged areas: Kriging (KG), Inverse Distance Weighting (IDW), and Storm Index (SI). To test the viability of these methods, historical data collected from 31 rain gauges distributed in central Chile, 35 degrees S to 38 degrees S, are used. As a result of the reduced number of rain gauges to evaluate the performance of each method, we used LOOCV (Leaving One Out Cross Validation). The results indicate that KG was limited due to the sparse distribution of rain gauges in central Chile. SI (a linear scaling method) showed the smallest prediction error in all of the ungauged locations, and outperformed both KG and IDW. However, the SI method does not provide estimates of uncertainty, as is possible with KG. The simplicity of SI renders it a viable method for extrapolating IDF curves to locations without data in the central zone of Chile.
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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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    Increases in the Amounts of Agricultural Surfaces and Their Impact on the Sustainability of Groundwater Resources in North-Central Chile
    (2024) Pizarro, Roberto; Borcoski, Francisca; Ingram, Ben; Bustamante-Ortega, Ramon; Sanguesa, Claudia; Ibanez, Alfredo; Toledo, Cristobal; Vidal, Cristian; Garcia-Chevesich, Pablo A.
    Water is a fundamental resource for Chile's productive structure, which is more important in arid areas, and especially with agricultural uses. This study was based on two basins (Cogot & iacute; and Illapel) located in the Coquimbo Region of north-central Chile. In this region, surface water rights were closed in 2002 and the only current option is the use of groundwater. These basins have high water demands due to the use of surface and groundwater for agricultural purposes, a fact that should influence the sustainability of groundwater reserves over time. The objective of this study was to determine how much agricultural use has affected the availability of groundwater in two basins. Under the previous context, the evolution of agricultural irrigation surfaces was evaluated using Landsat images and forest classifications. Similarly, groundwater reserves were evaluated using the recessive curves of hydrographs associated with the beginning of each hydrological year. The results show an increase in the agricultural area between 1996 and 2016, with a subsequent decrease, while groundwater reserves denoted significant decreases over time. In conclusion, a significant decrease in the volumes of groundwater reserves in both basins was observed, a decrease that is consistent with the increase in irrigated areas.
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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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    Temporal stability of within-field variability of total soluble solids of grapevine under semi-arid conditions: a first step towards a spatial model
    (2018) Verdugo Vásquez, Nicolás; Acevedo Opazo, César; Valdés Gómez, Héctor; Ingram, Ben; García de Cortázar-Atauri, Iñaki|Tisseyre, Bruno