Pedro Martínez-Santos

Vulnerability assessment of groundwater resources: A modelling-based approach to the Mancha Occidental aquifer, Spain

The semiarid Mancha Occidental aquifer represents a paradigmatic case of intensive groundwater use for agriculture. Irrigation has proven a catalyst for welfare in the area over the last three decades, if at a significant environmental cost and while raising concerns as to its mid-term sustainability. This paper describes an interdisciplinary exercise of scenario design and modelling, providing a methodology to couple hard-science numerical modelling approaches with the involvement of key water actors. Given the long-standing conflicts in the area, modelling work largely focuses on carrying out a vulnerability assessment rather than on trying to find solutions. The systems most resilient aspects and its drivers for change are identified, while their potential implications for aquifer sustainability are assessed under the light of the mandatory objectives established by the European Union Water Framework Directive for all Member States. Whereas modelling results imply that such objectives are unlikely to be met, a vulnerability assessment suggests that even adverse scenario pumping patterns could be sustained in the mid- to long-term (two to four decades).

Practices and Lessons Learned in Coping with Climatic Hazards at the River-Basin Scale: Floods and Droughts

Climatic hazards such as floods and droughts have always been a primary matter of concern for human populations. Severe floods damage settlements, transport networks, and arable land. Although devastating droughts are harmful primarily for agriculture and terrestrial ecosystems, they can also lead to local water supply shortages. Despite significant achievements in science and technology and success stories in environmental management in the 20th century, people still continue to suffer the consequences of climate hazards worldwide. This paper provides an overview of existing practices for coping with floods and droughts, compares strategies in different river basins, and outlines the areas that need improvement. First, the existing protection measures and response strategies against floods and droughts are briefly described. An overview is given of expected climate change and existing coping strategies for floods and droughts in seven case study basins. Four of the basins, namely the Elbe, Guadiana, Rhine, and Tisza, are located in Europe; the Nile and the Orange are in Africa; and the Amudarya is in Central Asia. Analysis of the coping strategies shows that structural measures exist in all seven river basins, but that nonstructural measures are generally not very extensive and/or advanced. Finally, the success stories in dealing with climatic hazards and lessons learned, taken partly from the seven case study basins and partly from literature, are summarized.

Comparative reflections on the use of modelling tools in conflictive water management settings: The Mancha Occidental aquifer, Spain

Participatory methods provide an increasingly accepted path to integrated assessment. This paper reflects on the role of two participatory modelling initiatives implemented in a highly conflictive setting: the Mancha Occidental aquifer, Spain. The methodologies are described within the context of the case study, examining their potential relevance to integrated assessment from a conceptual standpoint. The strengths and weaknesses of each approach are analysed in absolute and relative terms, attending to the different stages of the modelling process. The focus then shifts to explore the implications of this work within the context of participatory integrated assessment and scenario analysis. This serves the purpose of establishing the reasons why the tools have been useful in the eyes of stakeholders, and how the case-specific findings of this project may be relevant to other settings.

The DRASTIC-Sg model: an extension to the DRASTIC approach for mapping groundwater vulnerability in aquifers subject to differential land subsidence, with application to Mexico City

Mexico City relies on groundwater for most of its domestic supply. Over the years, intensive pumping has led to significant drawdowns and, subsequently, to severe land subsidence. Tensile cracks have also developed or reactivated as a result. All such processes cause damage to urban infrastructure, increasing the risk of spills and favoring contaminant propagation into the aquifer. The effects of ground deformation are frequently ignored in groundwater vulnerability studies, but can be relevant in subsiding cities. This report presents an extension to the DRASTIC methodology, named DRASTIC-Sg, which focuses on evaluating groundwater vulnerability in urban aquifers affected by differential subsidence. A subsidence parameter is developed to represent the ground deformation gradient (Sg), and then used to depict areas where damage risk to urban infrastructure is higher due to fracture propagation. Space-geodetic SqueeSAR data and global positioning system (GPS) validation were used to evaluate subsidence rates and gradients, integrating hydrogeological and geomechanical variables into a GIS environment. Results show that classic DRASTIC approaches may underestimate groundwater vulnerability in settings such as the one at hand. Hence, it is concluded that the Sg parameter is a welcome contribution to develop reliable vulnerability assessments in subsiding basins.RésuméLa ville de Mexico est dépendante de l’eau souterraine pour l’essentiel de son usage domestique. Au fil des années, les pompages intensifs ont conduit à des abaissements importants du niveau piézométrique et par conséquence à d’important affaissement de terrain. Des fissures de tension se sont développées ou ont été réactivées. Tous ces processus causent des dommages sur les infrastructures urbaines augmentant le risque de fuites favorisant la propagation de contaminants dans l’aquifère. Les effets des déformations du sol sont souvent ignorés dans les études de vulnérabilité des eaux souterraines, mais peuvent être pertinents pour les villes soumises à des affaissements de terrain. Cet article présente un développement de la méthodologie DRASTIC, nommée DRASTIC-Sg, ciblant l’évaluation de la vulnérabilité des eaux souterraines pour des aquifères en milieu urbain impactés par un affaissement différentiel des terrains. Un paramètre affaissement est développé pour représenter le gradient de déformation du sol, et ensuite utilisé pour décrire les zones où les risques de dommage des infrastructures urbaines sont plus élevés dus à la propagation des fractures. Les données spatiales et de géodésie (SqueeSAR) et les données de validation du système global de positionnement (GPS) ont été utilisées pour évaluer les vitesses d’affaissement des terrains et les gradients, intégrant les variables hydrogéologiques et géomécaniques dans un système d’information géographique. Les résultats montrent que les approches classiques DRASTIC sous-estiment la vulnérabilité des eaux souterraines dans des environnements tels que celui de la ville de Mexico. Par conséquence, on conclut que l’ajout du paramètre Sg contribue à élaborer des évaluations fiables de la vulnérabilité dans des bassins subsidents.ResumenLa ciudad de México depende del agua subterránea para la mayoría de sus abastecimientos domésticos. A través de los años, el bombeo intensivo ha llevado a depresiones significativas y, subsecuentemente, a una severa subsidencia del terreno. Como resultado también se han desarrollado o reactivado fracturas de tensión. Tales fenómenos han causado daños a la infraestructura urbana, incrementando el riesgo de vertidos y favoreciendo la propagación de contaminantes en el acuífero. Los efectos de la deformación del terreno son frecuentemente ignorados en los estudios de vulnerabilidad del agua subterránea, pero pueden ser relevantes en las ciudades subsidentes. Este trabajo presenta una extensión de la metodología DRASTIC, denominada DRASTIC-Sg, que se enfoca para evaluar la vulnerabilidad del agua subterránea en acuíferos afectados por subsidencia diferencial. Se desarrolla un parámetro de subsidencia para representar el gradiente de deformación del terreno (Sg), y luego se usa para delinear áreas donde el riesgo al daño para la infraestructura urbana es mayor debido a la propagación de las fracturas. Se usaron datos de espacio geodético SqueeSAR y la validación por el sistema de posicionamiento global (GPS) para evaluar las tasas y gradientes de subsidencia, integrando variables hidrogeológicas y geomecánicas en un ambiente GIS. Los resultados muestran que el enfoque DRASTIC clásico puede subestimar la vulnerabilidad del agua subterránea en configuraciones como la que nos ocupa. Por lo tanto, se concluye que el parámetro Sg es una contribución bienvenida para desarrollar evaluaciones confiables de vulnerabilidad en cuencas subsidentes.摘要墨西哥城大部分家庭用水依赖地下水。多年以来,强烈开采地下水 导致地下水水位大幅下降低,并由此造成严重的地面沉降。还使拉伸缝进 一步发育或使原来的拉伸缝再度激活。所有这些过程对城市基础设施造成 损坏,增加泄漏物和污染物进入含水层的风险。地面变形的影响在地下水 脆弱性研究中经常受到忽略,但在沉降的城市中有重要意义。本文介绍了 DRASTIC 方法的延伸,即DRASTIC-Sg。这个方法聚焦于评价受不同沉 降影响的城市含水层中地下水的脆弱性。找到了代表地面变形梯度(Sg)的 沉降参数,用来描述由于断裂蔓延造成对城市基础设施损害风险较高的地 区。太空大地测量SqueeSAR 资料和全球定验证用来评价沉降速度和梯 度,把水文地质变量和岩土力学变量整合在地理信息系统环境中。结果显 示,传统的DRASTIC 方法可能低估所研究的环境中地下水的脆弱性。因 此,结论就是,在进行沉降盆地可靠的脆弱性评价中,Sg 参数是一个积 极贡献。ResumoA Cidade do México depende de águas subterrâneas para a maior parte do seu abastecimento doméstico. Ao longo dos anos, bombeamentos intensivos levaram a significativos decréscimos do nível freático e, subsequentemente, a severa subsidência de terrenos. Como resultado, foram desenvolvidas ou reativadas fendas de tração. Todos estes processos causam danos nas infraestruturas urbanas, aumentando o risco de derramamentos e favorecendo a propagação da contaminação no aquífero. Os efeitos da deformação dos terrenos são frequentemente ignorados nos estudos de vulnerabilidade das águas subterrâneas, mas podem ser significativos em cidades sob subsidência. Este artigo apresenta uma extensão à metodologia DRASTIC, denominada DRASTIC-Sg, que se foca na avaliação da vulnerabilidade da água subterrânea em aquíferos urbanos afetados por subsidência diferencial. É desenvolvido um parâmetro de subsidência para representar o gradiente de deformação do solo (Sg), sendo depois usado para descrever áreas onde o risco de danos às infraestruturas urbanas é maior devido à propagação de fraturas. Foi usada validação com dados espaço-geodésicos SqueeSAR e sistemas de posicionamento global (GPS) para avaliar as taxas de subsidência e os gradientes, integrando variáveis hidrogeológicas e geomecânicas num ambiente SIG. Os resultados mostram que a abordagem DRASTIC clássica pode subestimar a vulnerabilidade da água subterrânea em ambientes como este. Conclui-se portanto que o parâmetro Sg é uma contribuição bem-vinda para o desenvolvimento de avaliações de vulnerabilidade em bacias em subsidência.

Does 91% of the world’s population really have “sustainable access to safe drinking water”?

Abstract Halving the number of people without sustainable access to safe drinking water was a core target of the Millennium Development Goals. This led to an unprecedented effort in the water sector, improving the livelihoods of millions of people. While the goal has officially been accomplished, unsuitable benchmarks have led to overstatement of the results. Indicators overemphasize improved water sources, disregarding the fact that many continue to be contaminated, unreliable or unaffordable. The alleged success needs to be reframed to avoid confusion, prevent investments from being reallocated away from the water sector and obtain more accurate estimates of water access.

Comparative performance of soil water balance models in computing semi-arid aquifer recharge

Abstract Estimating groundwater recharge is essential to ensure the sustainable use of groundwater resources, particularly in arid and semi-arid regions. Soil water balances have been frequently advocated as valuable tools to estimate groundwater recharge. This article compares the performance of three soil water balance models (Hydrobal, Visual Balan v2.0 and Thornthwaite) in the Ventós-Castellar aquifer, Spain. The models were used to simulate wet and dry years. Recharge estimates were transformed into water table fluctuations by means of a lumped groundwater model. These, in turn, were calibrated against piezometric data. Overall, the Hydrobal model shows the best fit between observed and calculated levels (r2 = 0.84), highlighting the role of soil moisture and vegetation in recharge processes. Editor D. Koutsoyiannis; Associate editor X. Chen Citation Touhami, I., et al., 2014. Comparative performance of soil water balance models in computing semi-arid aquifer recharge. Hydrological Sciences Journal, 59 (1), 193–203.

Legal Aspects Of Groundwater Ownership In Spain

Abstract Spains 1985 Water Law gave special significance to the Registry and the Catalogue, two legal figures that allowed the co‐existence of public and private groundwater ownership. Twenty years later, the situation of the Catalogue and the Registry is quite deficient. As a consequence, adequate groundwater management in Spain seems extremely difficult. This paper comments on the three main actions taken by the Government since 1985: first, the “Groundwater Registry and Catalogue Update Program” (ARYCA), a 42M€ project of the Ministry of Public Works, the results of which have not lived up to expectations; second, the Transient Disposition of the National Water Plan Law (2001) with regard to the “closure of the inscription period for private wells.” The results of this action are still uncertain; and thirdly, the “Update Program for the Registry and Catalogue Books” (ALBERCA), a 155M€ initiative of the Ministry of the Environment which is yet to be implemented.

Hydropolitics and Hydroeconomics of Shared Groundwater Resources: Experience in Arid and Semi-arid Regions

Interest on shared or transboundary aquifers management is relatively recent, but has already been useful in order to increase the awareness about the role of groundwater among politicians and high-level water decisionmakers. However, the process to achieve some kind of international convention or agreement on this issue will probably take a long time. Implementing international agreements on shared aquifers in arid and semiarid regions will be difficult if the current chaos in groundwater management is not previously 1 Paper presented in the Conference of the NATO ADVANCED STUDY INSTITUTE “OVEREXPLOITATION AND CONTAMINATION OF SHARED GROUNDWATER RESOURCES” Varna, Bulgaria October 1-12 2006 . To be published by Springer Verlag in 2007 in the NATO Security through Sciences Series-C Environmental Security ∗ To whom correspondence should be addressed. MANUEL RAMON LLAMAS MADURGA Royal Academy of Sciences. Valverde 22. 28034 Madrid. Email: mrllamas@geo.ucm.es GROUNDWATER HYDROPOLITICS AND HYDROECONOMICS 2 corrected. In this regard, this paper analyses the causes of this situation, and the concerns these raise in regard to sustainability. Later the paper considers the political and economics factors that affect groundwater development, as well as the social and legal aspects involved. Finally the paper reproduces the call for actions included in the Alicante Declaration, approved in January 2006 on occasion of the International Symposium on Groundwater Sustainability.

Resources Assessment of a Small Karstic Mediterranean Aquifer (South-Eastern, Spain)

Groundwater from small aquifer systems is frequently used for urban supply in southeastern Spain. Aquifers such as the Ventos system, located in Mediterranean semiarid environments, are sensitive to climatic and anthropogenic changes. Many of them have been severely depleted due to intensive pumping. Drawdowns in the Ventos aquifer amount to approximately 80 m over the last three decades. Adequate knowledge of groundwater resources is necessary for water planners and managers to guarantee suitable abstraction. This paper presents a methodology to estimate groundwater recharge in these kinds of quick-response semiarid karst aquifers. A distributed model has been used to evaluate the fraction of rainfall that ultimately results in aquifer recharge, as well as the correlation between the magnitude of rainfall events and infiltration rates. Modelling results are then compared with direct observations of the recharge processes and discussed to evaluate the implications of time scales.

A survey of domestic wells and pit latrines in rural settlements of Mali: Implications of on-site sanitation on the quality of water supplies

On-site sanitation is generally advocated as a means to eradicate the health hazards associated with open defecation. While this has provided a welcome upgrade to the livelihoods of millions of people in low-income countries, improved sanitation facilities are increasingly becoming a threat to domestic groundwater-based supplies. Within this context, a survey of pit latrines, domestic wells and improved water sources was carried out in a large rural village of southern Mali. All households were surveyed for water, sanitation and hygiene habits. Domestic wells and improved water sources were georeferenced and sampled for water quality (pH, electric conductivity, temperature, turbidity, total dissolved solids, thermotolerant coliforms, chloride and nitrate) and groundwater level, while all latrines were inspected and georeferenced. A GIS database was then used to evaluate the proportion of water points within the influence area of latrines, as well as to underpin multiple regression models to establish the determinants for fecal contamination in drinking supplies. Moreover, an appraisal of domestic water treatment practices was carried out. This revealed that nearly two-thirds of the population uses bleach to purify drinking supplies, but also that domestic-scale treatment as currently implemented by the population is far from effective. It is thus concluded that existing habits could be enhanced as a means to make water supplies safer. Furthermore, population, well and latrine density were all identified as statistically significant predictors for fecal pollution at different spatial scales. These findings are policy-relevant in the context of groundwater-dependent human settlements, since many countries in the developing world currently pursue the objective of eliminating open defecation.