Groundwater use is of fundamental importance to meet rapidly expanding urban, industrial, and agricultural water requirements, particularly in semiarid zones. To quantify the current rate of groundwater recharge is thus a prerequisite for efficient and sustainable groundwater resource management in these dry areas, where such resources are often the key to economic development. Increased groundwater recharge has been documented where native vegetation or forest/shrub land was converted to grassland or pasture, or where the land was cleared for agricultural purposes. The basic argument for increased recharge is that evapotranspiration, primarily interception and transpiration, is higher in shrublands than grasslands. Chloride mass balance (CMB) has been used to estimate ancient recharge, but recharge from recent land-use change has also been documented, specifically where vegetation has been altered and deep-rooted species replaced with shallow-rooted grasses. Chloride concentrations are inversely related to recharge rates: low Clconcentrations indicate high recharge rates as Cl- is leached from the system; high Cl concentrations indicate low recharge rates since Cl- accumulates as a result of evapotranspiration. The objectives were (1) to assess the hypothesis that removal of woody-shrub vegetation and replacement with grasses increases deep drainage, (2) to quantify the amount of deep drainage after land-use change, and (3) to provide science-based data for a better understanding of changing land-use impacts on deep drainage. Eight soils from five locations in the Central Rolling Red Plains near Abilene and Sweetwater were sampled. Each location consisted of a pair of similar soils with contrasting vegetative cover: shrubland and grassland. At each site three to five soil cores were taken as deep as possible and samples were taken by horizon, but horizons were split when their thickness exceeded 0.25 m. Soil Cl- profiles under shrubland at three sites showed that virtually no water escapes beyond the root zone. High Cl- concentrations and inventories reflect soil moisture fluxes that approached 0 mm yr-1 with depth. Evapotranspiration may be largely responsible for Cl- enrichment in those profiles. Surprisingly, soil moisture flux past 200 cm under juniper woodlands was the highest with 2.6 mm yr-1. Evapotranspirative Cl- enrichment in the upper 300 cm was not observed and may suggest a different water uptake mechanism for this plant community. Soil Cl- profiles showed increased recharge rates under grassland vegetation ecosystem. Estimated deep drainage past 200 cm of 0.1 to 1.3 mm yr-1 was observed. Low Cl- concentrations and inventories suggest a leaching environment that may be in response to changes in land use/land cover.

>Magister Scientiae - MSc / Previous studies have shown that the use of chloride mass balance (CMB) method is a suitable and practical approach to estimate groundwater recharge. This enables the prediction of groundwater availability to inform practical strategies for managing groundwater resources. However, such studies have largely applied the chloride mass balance method on national and catchment scales with limited focus on quaternary catchment level (QCL). Neglecting the chloride mass balance method at quaternary catchment level limits practical management and utilization of water resources at quaternary catchment level. The goal of the current study was to prove that 1) the chloride mass balance method should be applied at quaternary catchment level to ensure practical assessment of groundwater availability and that 2) chloride mass balance assessment should be accompanied with supplementary methods for its application in quaternary catchments of similar physiographic and hydrogeologic conditions. To achieve these goals, the present study assessed the application of chloride mass balance method on a pilot scale used alongside rainwater infiltration breakthrough (RIB) and water table fluctuation (WTF) methods to estimate the groundwater recharge as an indicator of groundwater availability. The pilot area (PA) was in the upper Berg River catchment in Western Cape in South Africa. Chloride concentrations were determined in groundwater samples collected from boreholes and rain water in rain gauges in the pilot area. Rainfall and borehole water levels in the pilot area were used in water table fluctuation and rainwater infiltration breakthrough analyses. As quality assurance, the specific yield data obtained from the pumping test were compared to those determined with the linear regression model. This established the reliability of the analysis i.e. the relationship between groundwater level and rainfall. Mean groundwater recharge values calculated using the chloride mass balance, rainwater infiltration breakthrough and water table fluctuation methods were 27.6 %, 23.67 %, and 22.7 % of the total precipitation received in the catchment, respectively. These results indicate that the use of these three methods have potential to estimate groundwater recharge at quaternary level which is the basic unit of water management in South Africa. These findings agree with previous studies conducted in the same catchment that indicate that mean groundwater recharge ranges between 18.6 % and 28 % of the total precipitation. In the future, these methods could be tested in catchments which have physiographic and hydrogeologic conditions similar to those of the current pilot area. / African Union (AU)

Ziel der Dissertation ist die hydrogeologische Charakterisierung von Karstgrundwasserleitern in der semi-ariden Klimazone, welche oftmals durch Übernutzung und anthropogene Verschmutz-ung bedroht sind. Trotz oft eingeschränkter Datenlage und einem unzureichenden Systemver-ständnis müssen quantitative und qualitative Faktoren, wie z.B. Grundwasserneubildungsrate, Aquiferparameter, Strömungs- und Stofftransportdynamik, Verschmutzungsempfindlichkeit und anthropogene Einflüsse quantifiziert werden. Jedoch können diese Gebiete auch günstige Eigenschaften für eine Charakterisierung, wie eine zeitlich eng begrenzte Impulsfunktion der Grundwasserneubildung durch intensive, kurze Niederschlagsereignisse sowie lange ungestörte Rezessionsperioden, aufweisen. Dies gilt für das in der Levante gelegene Untersuchungsgebiet. Die zeitliche und räumliche hydrologische Variabilität wurde durch ein ausgedehntes Messnetz hochaufgelöst erfasst. Zur Auswertung dieser Daten wurden konzeptionell korrekte, jedoch möglichst einfach anwendbare quantitative Verfahren und Modelle entwickelt und angewandt, was die Übertragbarkeit der Methoden auf weitere Trockengebiete ermöglicht. Durch eine Zusammenstellung und Auswertung hydrochemischer Langzeitdaten konnte die natürliche Hintergrundkonzentration von Chlorid im Grundwasser für 33 Quelleinzugsgebiete ermittelt werden. Darauf aufbauend war es möglich, durch eine Chloridmassenbilanz sowohl den langjährige mittlere Anteil der Grundwasserneubildung am Niederschlag (25–50%) zu bestimmen, als auch den Abwasseranteil im Quellwasser anhand rezenter Proben zu quantifizieren (0–20%). Anhand eines Speicher-Durchflussmodelles konnten sowohl Aquiferparameter im Einzugs-gebietsmaßstab als auch eine Tageszeitreihe der Grundwasserneubildung exemplarisch für die Auja-Quelle, die größte Süßwasserquelle im Unteren Jordantal, erfasst werden. Diese sowie weitere Quellen der Region sind durch ein „röhrengedrosseltes“ Abflussverhalten, d.h. eine Begrenzung der Quellschüttung, gekennzeichnet. Der hydrogeologisch komplexe Aquifer und das nichtlineare Systemverhalten bei Erreichen der maximalen Schüttung erfordern ein besonders angepasstes Modell, welches auch einen ausgeprägten hydraulischen Austausch zwischen den Karströhren und der geklüfteten Gesteinsmatrix berücksichtigen muss. Eine Reihe von Parametern konnte aus einer Rezessions- und Ereignis-Analyse der Abflussganglinie ermittelt werden. Das Speicher-Durchflussmodell benötigt lediglich sechs Kalibrierparameter und erlaubt eine sehr gute Simulation der Abflussganglinie. Die effektive Aquifer-Porosität wurde durch Kalibration ermittelt (ca. 2.4%). Über den simulierten 45-Jahres-Zeitraum führten die fünf niederschlagsreichsten Jahre zu einem Drittel der gesamten Grundwasserneubildung. Die zeitlich hoch aufgelösten Quellmessungen ermöglichten eine Quantifizierung der hydraulischen Reaktionszeiten sowie der mittleren Verweilzeiten, der Durchbruchsdauer und der relativen Anteile der schnellen Fließkomponente nach Niederschlagsereignissen. Diese Daten dienen sowohl einer Abschätzung der schnellen Neubildungsprozesse (vor allem Fokussierung im Epikarst und schnelles präferentielles Fließen durch die Vadose Zone) als auch einer Beurteilung der Verschmutzungsempfindlichkeit der Karstquellen. Weiterhin konnte eine Zugehörigkeit der beiden, 3500 m voneinander entfernten, artesischen Jericho-Quellen Sultan und Duyuk zu einem gemeinsamen Röhren- und damit Karstsystem nachgewiesen werden.

O estudo teve como objetivos a quantificação da interceptação das chuvas pelas copas das árvores e a estimativa da evapotranspiração real pelos métodos dos balanços hídrico e de cloreto. Para isso, estabeleceu-se o monitoramento de duas microbacias hidrográficas experimentais localizadas na Floresta Ombrófila Densa (Mata Atlântica), uma no Parque Estadual das Fontes do Ipiranga (PEFI) e a outra no Parque Estadual da Serra do Mar - Núcleo Cunha, ambas no Estado de São Paulo. As interceptações estimadas para o IAG-PEFI e para a microbacia B-Cunha foram de 21,6% e 24,0%, respectivamente. Os resultados das análises de regressão linear simples, entre a precipitação e a transprecipitação apresentaram coeficientes de determinação elevados para o IAG-PEFI (92,0%) e Cunha (88,6%), indicando que a variável independente explica maior proporção da variação da variável dependente. Para a interceptação foi aplicado o teste de correlação de Spearman (rs), sendo de 0,5449 para o IAG-PEFI e de 0,5243 para Cunha, indicando uma moderada correlação positiva, significativa para o nível de 5%. A pequena diferença encontrada na interceptação das chuvas pelas florestas para as duas localidades pode ser explicada pelas aberturas dos dosséis, no IAG-PEFI de 34,2% e Cunha de 31,1%. No ano hídrico de 2000 na microbacia do IAG-PEFI, a precipitação e o deflúvio totais foram de 1.279,6 mm e 273,4 mm. A evapotranspiração real alcançou 1.006,2 mm, representando 78,6% da precipitação total, indicando uma baixa produção hídrica (21,4%). Para os anos hídricos de 2001, 2002 e 2003 na microbacia B-Cunha, as evapotranspirações reais alcançaram 696,4 mm (42,8%), 769,5 mm (47,7%) e 748,4 mm (44,0%), com média de 738,1 mm (44,8%), indicando uma boa produção hídrica média (55,2%). Os fluxos totais de cloreto via deposição úmida nas microbacias do IAG-PEFI e B-Cunha foram de 7,26 e 7,57 kg.ha-1.ano-1, enquanto os fluxos totais através do rio alcançou 7,15 kg.ha-1.ano-1 e 7,96 kg.ha- 1.ano-1. Os resultados mostraram que os fluxos de entrada do íon foram muito próximos, indicando que o processo de urbanização que o entorno do PEFI sofreu não está influenciando nas precipitações. Na microbacia do IAG-PEFI a evapotranspiração real foi de 1.000,1 mm, correspondendo a 78,2% da precipitação total, valor este muito próximo ao método do balanço hídrico. Na microbacia BCunha a evapotranspiração real para os anos hídricos de 2001, 2002 e 2003 foi de 898,6 mm (55,2%), 696,7 mm (43,2%) e 693,7 mm (40,8%), e a média para os três anos de 763,0 mm (46,3%), valor ligeiramente superior ao obtido pelo balanço hídrico. Para as duas microbacias, os fluxos das entradas e das saídas do cloreto foram praticamente iguais. Então, podemos inferir que o íon não é um produto do intemperismo, e que seu envolvimento em troca iônica ou processos biológicos atingiu o equilíbrio. Portanto, esse íon pode ser considerado conservativo. A estimativa da evapotranspiração real pelo escoamento de base do mês de junho de 2000 na microbacia do IAG-PEFI, através do método do cloreto apresentou valor de 989,0 mm (77,3%). Já, na microbacia B-Cunha para agosto do ano hídrico de 2001, a evapotranspiração real foi de 450,5 mm (27,7%), valor muito abaixo do obtido pelos outros métodos, possivelmente pelo pequeno número de amostras realizadas. Para os meses de agosto e julho dos anos de 2002 e 2003 os resultados foram satisfatórios, alcançando 707,8 mm (43,9%) e 719,4 mm (42,3%). / The present study aims the quantification of the interception of the rains by the trees canopy and the determination of the real evapotranspiration by the methods of the water and the chloride balances. For that, it was established the monitory of two experimental catchments situated at Dense Ombrófila Forest (Atlantic Forest) one of them, in Parque Estadual das Fontes do Ipiranga (PEFI) and the other in Parque Estadual da Serra do Mar- Cunha Nucleus both in São Paulo State. The interceptions estimated for the IAG-PEFI and for the B-Cunha catchments were of 21.6% and 24.0%, at the same time. According to the D`Agostino-Pearson test for the transformed values, of the precipitation and the transprecipitation it was verified normal distribution at the level of significance 5%. The analysis results of simple linear regression presented coefficient of elevated determination for the IAG-PEFI (92.0%) and Cunha (88.6%). The analysis through the test of D`Agostino-Pearson for the absolute values and transformed from interception do not followed normal distribution. Thus, it was applied the test of correlation of Spearman, being of 0.545 for the IAG-PEFI and the 0.524 for Cunha showing a positive moderate correlation for the level of 5% significant. The small difference found in the interception of the rains through the forests for the two locations might be explained by the canopy openings in IAG-PEFI of 34.2% and Cunha of 31.1%. During the water year of 2000 in the catchment of IAG-PEFI, the precipitation and the total streamflow were of 1,279.6 mm and 273.4 mm. The real evapotranspiration reached 1,006.2 mm, representing 78.6% from total precipitation, indicating a low water production (21.4%) For the water years of 2001, 2002 and 2003 in the B-Cunha catchments, the real evapotranspiration reached 696.4 mm (42.8%), 769.5 mm (47.7%) and 748.4 mm (44.0%), with average of 738.1 mm (44.8%), indicating a good water production (55.2%). The chloride by wet deposition total flux in the IAG-PEFI and B-Cunha catchments were of 7.26 kg.ha-¹.year-1 and 7.57 kg.ha-¹.year-¹ and while the total flux through the streamflow were 7.15 kg.ha ¹.year-¹ and 7.96 kg.ha-¹.year-¹. The results showed that the ion enter flux were much closed, indicating that the urbanization process suffered by PEFI spilled is not influencing in the precipitations. In the IAGPEFI catchment, the estimated real evapotranspiration was of 1,000.1 mm, that correspond the 78.2% of the total precipitation a much closed value to the water balance. In the B-Cunha catchment the estimated real evapotranspiration for the water years of 2001, 2002 and 2003 was of 898.6 mm (55.2%), 693.7 mm (43.2%) and 693.7 mm (40.8%), and the medium for the three years of 763.0 mm (46.3%), value a little superior to that obtained in the water balance. For the two catchments, the input and output chloride flux were basically the same. Then, we could infer that the ion is not a product of intemperism, and that its involvement in ionic change, or biologic process reach the balance, however, this ion may be consider conservative. The estimative of real evapotranspiration by the base flow for June 2000 in the IAG-PEFI catchment, through the chloride method presented the value of 989.0 mm (77.3%). But in the B-Cunha catchment for August of the water year of 2001, the real evapotranspiration was of 450.5 mm (27.7%), value much lower obtained by the other methods, possible by the small number of sample realized. For the months of August and July of the 2002 and 2003 water years, the results were satisfactory, reaching 707.8 mm (43.9%) and 719.4 mm (43.3%).

O estudo teve como objetivos a quantificação da interceptação das chuvas pelas copas das árvores e a estimativa da evapotranspiração real pelos métodos dos balanços hídrico e de cloreto. Para isso, estabeleceu-se o monitoramento de duas microbacias hidrográficas experimentais localizadas na Floresta Ombrófila Densa (Mata Atlântica), uma no Parque Estadual das Fontes do Ipiranga (PEFI) e a outra no Parque Estadual da Serra do Mar - Núcleo Cunha, ambas no Estado de São Paulo. As interceptações estimadas para o IAG-PEFI e para a microbacia B-Cunha foram de 21,6% e 24,0%, respectivamente. Os resultados das análises de regressão linear simples, entre a precipitação e a transprecipitação apresentaram coeficientes de determinação elevados para o IAG-PEFI (92,0%) e Cunha (88,6%), indicando que a variável independente explica maior proporção da variação da variável dependente. Para a interceptação foi aplicado o teste de correlação de Spearman (rs), sendo de 0,5449 para o IAG-PEFI e de 0,5243 para Cunha, indicando uma moderada correlação positiva, significativa para o nível de 5%. A pequena diferença encontrada na interceptação das chuvas pelas florestas para as duas localidades pode ser explicada pelas aberturas dos dosséis, no IAG-PEFI de 34,2% e Cunha de 31,1%. No ano hídrico de 2000 na microbacia do IAG-PEFI, a precipitação e o deflúvio totais foram de 1.279,6 mm e 273,4 mm. A evapotranspiração real alcançou 1.006,2 mm, representando 78,6% da precipitação total, indicando uma baixa produção hídrica (21,4%). Para os anos hídricos de 2001, 2002 e 2003 na microbacia B-Cunha, as evapotranspirações reais alcançaram 696,4 mm (42,8%), 769,5 mm (47,7%) e 748,4 mm (44,0%), com média de 738,1 mm (44,8%), indicando uma boa produção hídrica média (55,2%). Os fluxos totais de cloreto via deposição úmida nas microbacias do IAG-PEFI e B-Cunha foram de 7,26 e 7,57 kg.ha-1.ano-1, enquanto os fluxos totais através do rio alcançou 7,15 kg.ha-1.ano-1 e 7,96 kg.ha- 1.ano-1. Os resultados mostraram que os fluxos de entrada do íon foram muito próximos, indicando que o processo de urbanização que o entorno do PEFI sofreu não está influenciando nas precipitações. Na microbacia do IAG-PEFI a evapotranspiração real foi de 1.000,1 mm, correspondendo a 78,2% da precipitação total, valor este muito próximo ao método do balanço hídrico. Na microbacia BCunha a evapotranspiração real para os anos hídricos de 2001, 2002 e 2003 foi de 898,6 mm (55,2%), 696,7 mm (43,2%) e 693,7 mm (40,8%), e a média para os três anos de 763,0 mm (46,3%), valor ligeiramente superior ao obtido pelo balanço hídrico. Para as duas microbacias, os fluxos das entradas e das saídas do cloreto foram praticamente iguais. Então, podemos inferir que o íon não é um produto do intemperismo, e que seu envolvimento em troca iônica ou processos biológicos atingiu o equilíbrio. Portanto, esse íon pode ser considerado conservativo. A estimativa da evapotranspiração real pelo escoamento de base do mês de junho de 2000 na microbacia do IAG-PEFI, através do método do cloreto apresentou valor de 989,0 mm (77,3%). Já, na microbacia B-Cunha para agosto do ano hídrico de 2001, a evapotranspiração real foi de 450,5 mm (27,7%), valor muito abaixo do obtido pelos outros métodos, possivelmente pelo pequeno número de amostras realizadas. Para os meses de agosto e julho dos anos de 2002 e 2003 os resultados foram satisfatórios, alcançando 707,8 mm (43,9%) e 719,4 mm (42,3%). / The present study aims the quantification of the interception of the rains by the trees canopy and the determination of the real evapotranspiration by the methods of the water and the chloride balances. For that, it was established the monitory of two experimental catchments situated at Dense Ombrófila Forest (Atlantic Forest) one of them, in Parque Estadual das Fontes do Ipiranga (PEFI) and the other in Parque Estadual da Serra do Mar- Cunha Nucleus both in São Paulo State. The interceptions estimated for the IAG-PEFI and for the B-Cunha catchments were of 21.6% and 24.0%, at the same time. According to the D`Agostino-Pearson test for the transformed values, of the precipitation and the transprecipitation it was verified normal distribution at the level of significance 5%. The analysis results of simple linear regression presented coefficient of elevated determination for the IAG-PEFI (92.0%) and Cunha (88.6%). The analysis through the test of D`Agostino-Pearson for the absolute values and transformed from interception do not followed normal distribution. Thus, it was applied the test of correlation of Spearman, being of 0.545 for the IAG-PEFI and the 0.524 for Cunha showing a positive moderate correlation for the level of 5% significant. The small difference found in the interception of the rains through the forests for the two locations might be explained by the canopy openings in IAG-PEFI of 34.2% and Cunha of 31.1%. During the water year of 2000 in the catchment of IAG-PEFI, the precipitation and the total streamflow were of 1,279.6 mm and 273.4 mm. The real evapotranspiration reached 1,006.2 mm, representing 78.6% from total precipitation, indicating a low water production (21.4%) For the water years of 2001, 2002 and 2003 in the B-Cunha catchments, the real evapotranspiration reached 696.4 mm (42.8%), 769.5 mm (47.7%) and 748.4 mm (44.0%), with average of 738.1 mm (44.8%), indicating a good water production (55.2%). The chloride by wet deposition total flux in the IAG-PEFI and B-Cunha catchments were of 7.26 kg.ha-¹.year-1 and 7.57 kg.ha-¹.year-¹ and while the total flux through the streamflow were 7.15 kg.ha ¹.year-¹ and 7.96 kg.ha-¹.year-¹. The results showed that the ion enter flux were much closed, indicating that the urbanization process suffered by PEFI spilled is not influencing in the precipitations. In the IAGPEFI catchment, the estimated real evapotranspiration was of 1,000.1 mm, that correspond the 78.2% of the total precipitation a much closed value to the water balance. In the B-Cunha catchment the estimated real evapotranspiration for the water years of 2001, 2002 and 2003 was of 898.6 mm (55.2%), 693.7 mm (43.2%) and 693.7 mm (40.8%), and the medium for the three years of 763.0 mm (46.3%), value a little superior to that obtained in the water balance. For the two catchments, the input and output chloride flux were basically the same. Then, we could infer that the ion is not a product of intemperism, and that its involvement in ionic change, or biologic process reach the balance, however, this ion may be consider conservative. The estimative of real evapotranspiration by the base flow for June 2000 in the IAG-PEFI catchment, through the chloride method presented the value of 989.0 mm (77.3%). But in the B-Cunha catchment for August of the water year of 2001, the real evapotranspiration was of 450.5 mm (27.7%), value much lower obtained by the other methods, possible by the small number of sample realized. For the months of August and July of the 2002 and 2003 water years, the results were satisfactory, reaching 707.8 mm (43.9%) and 719.4 mm (43.3%).