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Detailed investigation of small watershed systems in southern Portugal, implementing a multi-method recharge estimation comparison
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Abstract(s)
Este estudo aborda uma analise completa da recarga dos aquíferos, assim como os seus
factores climáticos e hidrológicos, dentro de um pequeno sistema de bacias hidrográficas em
Portugal, na região semiárida do Algarve. Foram coletados na região durante os meses de
maior pluviosidade vários diferentes conjuntos de dados derivados, obtidos entre novembro
de 2020 e abril de 2021. Dentro das séries de dados há factores como, temperatura,
precipitação e evapotranspiração, assim como medidas piezométricas em campo. A
distribuição dos factores climáticos foi estudada com o uso de métodos de interpolação de
dados em grelha, revelando uma mínima variação espacial na região estudada. O estudo
estatístico demonstra uma forte correlação entre os factores climáticos e medidas dos níveis
dos aquíferos, sugerindo que há uma resposta rápida dos aquíferos às flutuações climáticas.
Os coeficientes de correlação foram 0.7 a 0.8 para precipitação e -0.3 a -0.4 para temperatura
e potencial de evapotranspiração. Além disso, foi observado que o próprio sistema do
aquífero é bem conectado na região estudada, com coeficientes de correlação maiores que
0.9 para as medidas piezométricas. Ainda, utilizando os dados coletados, múltiplas técnicas
foram implementadas na área de estudo para estimar o valor de recarga do aquífero durante
o período de observação, resultando em dois modelos de recarga que apresentaram um bom
desempenho. Os métodos e as incertezas dos dois modelos, BALSEQ e LUMPREM, foram
comparados em detalhes a fim de avaliar a significância e as imprecisões em suas simulações
do período de observação. O modelo BALSEQ sugere que a recarga varia de 81.58 a 160.32
mm, e de acordo com o modelo LUMPREM, a recarga varia de 16.97 a 93.67 mm. No entanto,
a avaliação do desempenho dos modelos sugere que, nas duas abordagens, a variação dos
resultados de sobreposição, entre 80 e 90 mm de recarga, é a mais significativa.
This study includes a thorough examination of groundwater recharge, as well as its hydrogeological and climatic drivers, within a small watershed system in Portugal’s semi-arid Algarve region. Several different derived data sets were collected over the region’s most significant rain months, over a 5-month period between November 2020 and April 2021. Among the data sets are climate factors including temperature, precipitation, and evapotranspiration, as well as various in field piezometric measurements. Using interpolation methods of gridded data, the geographical distribution of climatic drivers was studied, visualizing and describing the minimal spatial variation within the research region. The statistical study of the climatic factors and measured groundwater levels indicated a strong relationship, suggesting rapid groundwater responses to climate fluctuations, with correlations coefficients of 0.7 to 0.8 regarding the precipitation and -0.3 to -0.4 regarding temperature and potential evapotranspiration. Furthermore, it showed that the groundwater system itself is well connected throughout the region, with most corelation coefficients above 0.9 between the piezometric measurements. Utilizing the gathered data, multiple techniques to estimate the recharge value during the observation period were implemented on the study location, resulting in two distinct recharge models with good performance. The methods and uncertainties of the two models, BALSEQ and LUMPREM were compared in detail in order to assess the significance and inaccuracies in their simulations of the observation period. According to the BALSEQ model, recharge varies from 81.58 to 160.32 mm, and according to the LUMPREM model, recharge ranges from 16.97 to 93.67 mm. However, the evaluation of performances of the models suggests that the overlapping result range of the two approaches, between 80 and 90 mm of recharge, is the most significant.
This study includes a thorough examination of groundwater recharge, as well as its hydrogeological and climatic drivers, within a small watershed system in Portugal’s semi-arid Algarve region. Several different derived data sets were collected over the region’s most significant rain months, over a 5-month period between November 2020 and April 2021. Among the data sets are climate factors including temperature, precipitation, and evapotranspiration, as well as various in field piezometric measurements. Using interpolation methods of gridded data, the geographical distribution of climatic drivers was studied, visualizing and describing the minimal spatial variation within the research region. The statistical study of the climatic factors and measured groundwater levels indicated a strong relationship, suggesting rapid groundwater responses to climate fluctuations, with correlations coefficients of 0.7 to 0.8 regarding the precipitation and -0.3 to -0.4 regarding temperature and potential evapotranspiration. Furthermore, it showed that the groundwater system itself is well connected throughout the region, with most corelation coefficients above 0.9 between the piezometric measurements. Utilizing the gathered data, multiple techniques to estimate the recharge value during the observation period were implemented on the study location, resulting in two distinct recharge models with good performance. The methods and uncertainties of the two models, BALSEQ and LUMPREM were compared in detail in order to assess the significance and inaccuracies in their simulations of the observation period. According to the BALSEQ model, recharge varies from 81.58 to 160.32 mm, and according to the LUMPREM model, recharge ranges from 16.97 to 93.67 mm. However, the evaluation of performances of the models suggests that the overlapping result range of the two approaches, between 80 and 90 mm of recharge, is the most significant.
Description
Keywords
Groundwater Recharge estimation Climate factors Hydrogeology