scholarly journals A soil moisture monitoring network to characterize karstic recharge and evapotranspiration at five representative sites across the globe

Author(s):  
Romane Berthelin ◽  
Michael Rinderer ◽  
Bartolomé Andreo ◽  
Andy Baker ◽  
Daniela Kilian ◽  
...  

Abstract. Karst systems that are characterized by a high subsurface heterogeneity are posing a challenge to study their complex recharge processes. Experimental methods to study karst processes mostly focus on characterizing the entire aquifer. Despite their important role for recharge processes, the limited focus has been given on studies of the soil and epikarst and most available research has been performed at sites of similar latitudes. In our study, we describe a new monitoring concept that allows the improvement of soil and epikarst processes understanding by covering different karst systems with different land cover at different climate regions. First, we describe the site selection and the experimental setup. Then we describe the five individual sites and their soil profiles. We also present some preliminary data and highlight the potential of the data for future research aimed at answering the relevant research questions: (1) How do the soil and epikarst heterogeneities influence water flow and storage processes in the karst vadose zone? (2) What is the impact of the land cover type on karstic groundwater recharge and evapotranspiration? (3) What is the impact of climate on karstic groundwater recharge and evapotranspiration? In order to answer these questions, we monitor soil moisture, which controls the partitioning of rainfall into infiltration, soil water storage, evapotranspiration, and groundwater recharge processes. We installed a soil moisture-monitoring network at five different climate regions: in Puerto Rico (tropical), Spain (Mediterranean), the United Kingdom (humid oceanic), Germany (humid mountainous), and Australia (dry semi-arid). At each of the five sites, we defined two 20 m × 20 m plots to install soil moisture probes under different land use types (forest and grassland). At each plot, 15 soil moisture profiles were installed with probes at different depths from the top soil to the epikarst (over 400 soil moisture probes were installed). Our first results show that the monitoring network provides new insights into the soil moisture dynamics of the five study sites and that significant differences prevail among forest and grassland sites. Some profiles are characterized by sequential reactions of soil moisture, i.e., the uppermost probe reacts first and the lowest probe reacts last, while at other profiles, we find non-sequential reactions that we interpret to result from preferential flow processes. While the former favours storage in the soil providing water for evapotranspiration, the latter can be seen as an indicator for the initiation of fast and preferential recharge into the karst system. Covering the spatiotemporal variability of these processes through a large number of installed probes, our monitoring network will allow to develop a new conceptual understanding of evapotranspiration and groundwater recharge processes in karst regions across different climate regions and land use types, and provide the base for quantitative assessment with physically-based modelling approaches in the future.

2020 ◽  
Vol 9 (1) ◽  
pp. 11-23 ◽  
Author(s):  
Romane Berthelin ◽  
Michael Rinderer ◽  
Bartolomé Andreo ◽  
Andy Baker ◽  
Daniela Kilian ◽  
...  

Abstract. Karst systems are characterized by a high subsurface heterogeneity, and their complex recharge processes are difficult to characterize. Experimental methods to study karst systems mostly focus on analysing the entire aquifer. Despite their important role in recharge processes, the soil and epikarst receive limited attention, and the few available studies were performed at sites of similar latitudes. In this paper, we describe a new monitoring network that allows for the improvement of the understanding of soil and epikarst processes by including different karst systems with different land-cover types in different climate regions. Here, we present preliminary data form the network and elaborate on their potential to answer research questions about the role of soil and epikarst on karstic water flow and storage. The network measures soil moisture at multiple points and depths to understand the partitioning of rainfall into infiltration, evapotranspiration, and groundwater recharge processes. We installed soil moisture probes at five different climate regions: Puerto Rico (tropical), Spain (Mediterranean), the United Kingdom (humid oceanic), Germany (humid mountainous), and Australia (dry semi-arid). At each of the five sites, we defined two 20 m×20 m plots with different land-use types (forest and grassland). At each plot, 15 soil moisture profiles were randomly selected and probes at different depths from the topsoil to the epikarst (in total over 400 soil moisture probes) were installed. Covering the spatio-temporal variability of flow processes through a large number of profiles, our monitoring network will allow researchers to develop a new conceptual understanding of evapotranspiration and groundwater recharge processes in karst regions across different climate regions and land-use types, and this will provide the base for quantitative assessment with physically based modelling approaches in the future.


Geologos ◽  
2019 ◽  
Vol 25 (3) ◽  
pp. 231-240 ◽  
Author(s):  
Anna Kuczyńska

Abstract The present paper discusses the results of an analysis of the impact of land use on the distribution of pharmaceuticals in groundwater samples collected during a pilot study of the contents of pharmaceuticals and hormones in ground-water taken from the national groundwater monitoring network of the Polish Geological Institute - National Research Institute. Samples were collected during monitoring campaigns from 160 groundwater monitoring sites in various land use types in 2016 and 2017. Samples were analysed for a total of 34 active substances, including natural and synthetic oestrogen hormones, cardiovascular and respiratory medications, analgesics and anti-inflammatories, antidepressants, antimicrobial drugs and anti-epileptics. Our study confirmed the presence of pharmaceuticals in 53 per cent of ground-water samples taken. Data show variations in the distribution of pharmaceuticals depending on land use type, which can thus be employed in pressure analysis and identification of sources of pollution.


Earth ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 556-585
Author(s):  
Kassim Ramadhani Mussa ◽  
Ibrahimu Chikira Mjemah ◽  
Revocatus Lazaro Machunda

The response of aquifers with contrasting climate and geology to climate and land cover change perturbations through natural groundwater recharge remains inadequately understood. In Tanzania and elsewhere in the world, studies have been conducted to assess the impact of climate change and variability, and land use/cover changes on stream flow using different models, but similar studies on groundwater dynamics are inadequate. This study, therefore, examined the influence of land use/cover and climate dynamics on natural groundwater recharge in basins with contrasting climate and geology in Tanzania, applying the modified soil moisture balance method, coupled with the curve number (CN). The method hinges on the balance between the incoming water from precipitation and the outflow of water by evapotranspiration. The different parameters in the soil moisture balance method were computed using the Thornthwaite Water Balance software. The potential evapotranspiration (PET) was calculated using the daily maximum and minimum temperatures, utilizing two-temperature-based PET methods, Penman–Monteith (PM) and Hargreaves–Samani (HS). The rainfall data were obtained from the gauging stations under the Tanzania Meteorological Agency and some additional data were acquired from climate observatories management by water basins. The results show that there has been a quasi-stable CN in the Singida semi-arid, fractured crystalline basement aquifer (74.2 in 1997, 73.64 in 2005, and 73.87 in 2018). In the Kimbiji, humid, Neogene sedimentary aquifer, the CN has been steadily increasing (66.69 in 1997, 69.08 in 2008, and 71.42 in 2016), indicating the rapid land cover changes in the Kimbiji aquifer as compared to the Singida aquifer. For the Kimbiji humid aquifer, the PET calculated using the Penman–Monteith (PM) method for the 1996/1997, 2007/2008, and 2015/2016 hydrological years were 1156.5, 1079.5, and 1143.9 mm/year, respectively, while for the Hargreaves–Samani (HS) method, the PET was found to be 1046.1, 1138.3, and 1204.4 mm/year for the 1996/1997, 2007/2008, and 2015/2016 hydrological years, respectively. For the Singida semi-arid aquifer, the PM PET method resulted in 2083.3, 2053.6, and 1875.4 mm/year for the 1996/1997, 2004/2005, and 2017/2018 hydrological years, respectively. The HS method produced relatively lower PET values for the semi-arid area (1839.4, 1814.7, and 1710.2 mm/year) for the 1996/1997, 2004/2005, and 2017/2018 hydrological years, respectively. It was equally revealed that the recharge and aridity indices correspond with the PET calculated using two temperature-dependent methods. The decline of certain land covers (forests) and increase in others (built-up areas) have contributed to the increase in surface runoff in each study area, possibly resulting in the decreasing trend of groundwater recharge. An overestimation of the PET using the HS method in the Kimbiji humid aquifer was observed, which was relatively smaller than the overestimation of the PET using the PM method in the Singida semi-arid aquifer. Despite the difference in climate and geology, the response of the two aquifers to rainfall is similar. The combined influence of climate and land cover changes on natural groundwater recharge was observed to be prominent in the Kimbiji aquifer, while only climate variability appreciably influences natural groundwater recharge in the Singida semi-arid aquifer. El Nino and the Southern Oscillation as part of the climate variability phenomenon dwarfed the time lags between rainfall and recharge in the two basins, regardless of their difference in climate and geology.


Author(s):  
Tsedekech Gebremeskel Weldmichael ◽  
Erika Michéli ◽  
Barbara Simon

Land use change may modify key soil attributes, influencing the capacity of soil to maintain ecological functions. Understanding the effects of land use types (LUTs) on soil properties is, therefore, crucial for the sustainable utilization of soil resources. This study aims to investigate the impact of LUT on primary soil properties. Composite soil samples from eight sampling points per LUT (forest, grassland, and arable land) were taken from the top 25 cm of the soil in October 2019. The following soil physicochemical parameters were investigated according to standard protocols: soil organic matter (SOM), pH, soil moisture, NH4+–N, NO3––N, AL-K2O, AL-P2O5, CaCO3, E4/E6, cation exchange capacity (CEC), base saturation (BS), and exchangeable bases (Ca2+, Mg2+, K+, and Na+). Furthermore, soil microbial respiration (SMR) was determined based on basal respiration method. The results indicated that most of the investigated soil properties showed significant difference across LUTs, among which NO3––N, total N, and K2O were profoundly affected by LUT (p ≤ 0.001). On the other hand, CEC, soil moisture, and Na+ did not greatly change among the LUTs (p ≥ 0.05). Arable soils showed the lowest SOM content and available nitrogen but the highest content of P2O5 and CaCO3. SMR was considerably higher in grassland compared to arable land and forest, respectively. The study found a positive correlation between soil moisture (r = 0.67; p < 0.01), Mg2+ (r = 0.61; p < 0.01), and K2O (r = 0.58; p < 0.05) with SMR. Overall, the study highlighted that agricultural practices in the study area induced SOM and available nitrogen reduction. Grassland soils were more favorable for microbial activity.


2021 ◽  
Author(s):  
Rita M. Cardoso ◽  
Daniela D. C. A. Lima ◽  
Pedro M. M. Soares ◽  
Diana Rechid ◽  
Marcus Breil ◽  
...  

&lt;p&gt;Land-atmosphere energy and water exchanges are fundamentally linked to soil-moisture. The distribution of the planets&amp;#8217; biomes hinges on the surface-atmosphere coupling since soil moisture and temperature feedbacks have a strong influence on plant transpiration and photosynthesis. Land use/land cover changes (LUC) modify locally land surface properties that control the land-atmosphere mass, energy, and momentum exchanges. The impact of these changes depends on the scale and nature of land cover modifications and is very difficult to quantify. However, large inconsistencies in the LUC impacts are observed between models, highlighting the need for common LUC across a large ensemble of models. The Flagship Pilot Study LUCAS (Land Use &amp; Climate Across Scales) provides a coordinated effort to study LUC using an ensemble of regional climate models (RCMs). In the first phase of the project 3 experiments were performed for continental Europe: EVAL (current climate); GRASS (trees replaced by grassland) and FOREST (grasses and shrubs replaced by trees). &amp;#160;An analysis of the energy and moisture balance for the three experiments is performed, focusing on the relationship between the fluxes partitioning, heat waves and droughts. To better asses the link between extreme temperatures and soil moisture or evapotranspiration, a new coupling metric for short time scales is proposed, the Latent Heat Flux-Temperature Coupling Magnitude (LETCM). This new metric is computed for a specific period, considering the positive temperature extremes and the negative latent heat flux extremes. Areas with positive magnitude values imply higher temperature anomaly, due to a negative latent heat flux anomaly. This new metric only considers periods of strong coupling, with positive signals in areas of high temperatures and evaporative stress, allowing for the detection of events that are extreme for energy and water cycle. Concurrently, a new decile based normalised drought index is used to examine the concurrent heat extremes and droughts. The analysis focuses on the three experiments revealing that the number, amplitude and spatial distribution of compound extreme heat and drought is highly model dependant. The impact of afforestation or deforestation is not consistent across models.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgements&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;The authors wish to acknowledge project LEADING (PTDC/CTA-MET/28914/2017) and FCT - project UIDB/50019/2020 - Instituto Dom Luiz.&lt;/p&gt;


2018 ◽  
Vol 69 (3) ◽  
pp. 160-168
Author(s):  
Jozef Varga ◽  
Radoslava Kanianska ◽  
Ján Spišiak

Abstract The aim of the study was to analyse the impact of land use and altitudinal gradient including geological conditions on selected soil physical properties with subsequent effect on earthworms as important soil organisms. The research was conducted at three study sites (Očová – OC, Tajov – TA, Liptovská Teplička – LT) situated in the different climatic and natural conditions of Slovakia each with 3 plots differing in land use (arable land - AL, permanent grasslands – PG, forest land – FL). During 2014 over two periods, we measured soil penetration resistance (PR) with total depth of the measurement (DP) and soil moisture (SM). Earthworms were hand sorted counted and weighed. We found out high variability of measured parameters conditioned by time, space (altitudinal gradient) and land use. PR values of all measurements ranged from 0.19 to 5.00 MPa, DP values from 0.02 to 0.80 m and soil moisture from 2 to 50%. Paired samples test confirmed differences between different land use types mainly between AL and FL plots. There were confirmed significant differences between three ecological gradients in all observed properties with one exception. Correlations among observed variables under different altitudinal gradients and land use types were found. The earthworm density and biomass was significantly higher in permanent grasslands compared to forest and arable land. In arable land, the earthworm density and biomass negatively correlated with the penetration resistance and positively with the depth of the total measurements. In permanent grasslands earthworm biomass positively correlated with soil moisture.


2020 ◽  
Vol 7 (1) ◽  
pp. 91
Author(s):  
Júlio Barboza Chiquetto ◽  
Maria Elisa Siqueira Silva ◽  
Rita Yuri Ynoue ◽  
Flávia Noronha Dutra Ribieiro ◽  
Débora Souza Alvim ◽  
...  

A poluição do ar é influenciada por fatores naturais e antropogênicos. Quatro pontos de monitoramento (veicular, comercial, residencial e background urbano (BGU))da poluição do ar em São Paulo foram avaliados durante 16 anos, revelando diferenças significativas devidoao uso do solo em todas as escalas temporais. Na escala diurna, as concentrações de poluentes primários são duas vezes mais altas nos pontos veicular e residencial do que no ponto BGU, onde a concentração de ozonio (O3) é 50% mais alta. Na escala sazonal, as concentrações de monóxido de carbono(CO) variaram em 80% devido ao uso do solo, e 55% pela sazonalidade.As variações sazonais ede uso do solo exercem impactos similares nas concentrações de O3 e monóxido de nitrogênio (NO). Para o material particulado grosso (MP10) e o dióxido de nitrogênio(NO2), as variações sazonais são mais intensas do que as por uso do solo. Na série temporal de 16 anos, o ponto BGU apresentou correlações mais fortes e significativas entre a média mensal de ondas longas (ROL) e o O3 (0,48) e o MP10 (0,37), comparadas ao ponto veicular (0,33 e 0,22, respectivamente). Estes resultados confirmam que o uso do solo urbano tem um papel significativo na concentração de poluentes em todas as escalas de análise, embora a sua influência se torne menos pronunciada em escalas maiores, conforme a qualidade do ar transita de um sistema antropogênico para um sistema natural. Isto poderá auxiliar decisões sobre políticas públicas em megacidades envolvendo a modificação do uso do solo.


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