Ana Mijic

Panta Rhei 2013–2015: global perspectives on hydrology, society and change

ABSTRACT In 2013, the International Association of Hydrological Sciences (IAHS) launched the hydrological decade 2013–2022 with the theme “Panta Rhei: Change in Hydrology and Society”. The decade recognizes the urgency of hydrological research to understand and predict the interactions of society and water, to support sustainable water resource use under changing climatic and environmental conditions. This paper reports on the first Panta Rhei biennium 2013–2015, providing a comprehensive resource that describes the scope and direction of Panta Rhei. We bring together the knowledge of all the Panta Rhei working groups, to summarize the most pressing research questions and how the hydrological community is progressing towards those goals. We draw out interconnections between different strands of research, and reflect on the need to take a global view on hydrology in the current era of human impacts and environmental change. Finally, we look back to the six driving science questions identified at the outset of Panta Rhei, to quantify progress towards those aims. Editor D. Koutsoyiannis; Associate editor not assigned

CO2 injectivity in saline aquifers: The impact of non‐Darcy flow, phase miscibility, and gas compressibility

A key aspect of CO2 storage is the injection rate into the subsurface, which is limited by the pressure at which formation starts to fracture. Hence, it is vital to assess all of the relevant processes that may contribute to the pressure increase in the aquifer during CO2 injection. Building on an existing analytical solution for immiscible and spatially varying non-Darcy flow, this paper presents a mathematical model that accounts for combined effects of non-Darcy flow, phase miscibility, and gas compressibility in radial two-phase displacements. Results show that in low-permeability formations when CO2 is injected at high rates, non-Darcy simulations forecast better displacement efficiency compared to flow under Darcy conditions. This will have a positive effect on the formation CO2 storage capacity. This, however, comes at the cost of increased well pressures. More favorable estimations of the pressure buildup are obtained when CO2 compressibility is taken into account because reservoir pressures are reduced due to the change in the gas phase properties. Also, non-Darcy flow results in a significant reduction in halite precipitation in the near-well region, with a positive effect on CO2 injectivity. In the examples shown, non-Darcy flow conditions may lead to significantly different pressure and saturation distributions in the near-well region, with potentially important implications for CO2 injectivity.

Multiple Well Systems with Non-Darcy Flow

Optimization of groundwater and other subsurface resources requires analysis of multiple-well systems. The usual modeling approach is to apply a linear flow equation (e.g., Darcys law in confined aquifers). In such conditions, the composite response of a system of wells can be determined by summating responses of the individual wells (the principle of superposition). However, if the flow velocity increases, the nonlinear losses become important in the near-well region and the principle of superposition is no longer valid. This article presents an alternative method for applying analytical solutions of non-Darcy flow for a single- to multiple-well systems. The method focuses on the response of the central injection well located in an array of equally spaced wells, as it is the well that exhibits the highest pressure change within the system. This critical well can be represented as a single well situated in the center of a closed square domain, the width of which is equal to the well spacing. It is hypothesized that a single well situated in a circular region of the equivalent plan area adequately represents such a system. A test case is presented and compared with a finite-difference solution for the original problem, assuming that the flow is governed by the nonlinear Forchheimer equation.

Historical and future land-cover changes in the Upper Ganges basin of India

The green revolution represents one of the greatest environmental changes in India over the last century. The Upper Ganges (UG) basin is experiencing rapid rates of change of land cover and irrigation practices. In this study, we investigated the historical rate of change and created future scenario projections by means of 30 m-resolution multi-temporal Landsat 5 Thematic Mapper and Landsat 7 Enhanced Thematic Mapper Plus data of the UG basin. Post-classification change analysis methods were applied to Landsat images in order to detect and quantify land-cover changes in the UG basin. Subsequently, Markov chain analysis was applied to project future scenarios of land-cover change. Fifteen different scenarios were generated based on historic land-cover change. These scenarios diverged in terms of future projections, highlighting the dynamic nature of the changes. This study has shown that between the years 1984 and 2010 the main land-cover change trends are conversion from shrubs to forest (+4.7%), urbanization (+5.8%), agricultural expansion (+1.3%), and loss of barren land (–9.5%). The land-cover change patterns in the UG basin were mapped and quantified, showing the capability of Landsat data in providing accurate land-cover maps. These results, in combination with those derived from the Markov model, provide the necessary evidence base to support regional land-use planning and develop future-proof water resource management strategies.

Antifragility and the development of urban water infrastructure

Abstract Antifragility is a system property that results in systems becoming increasingly resistant to external shocks by being exposed to them. These systems have the counter-intuitive property of benefiting from uncertain conditions. This paper presents one of the first known applications of antifragility to water infrastructure systems and outlines the development of antifragility at the city scale through the use of local governance, data collection and a bimodal strategy for infrastructure development. The systems architecture presented results in a management paradigm that can deliver reliable water systems in the face of highly uncertain future conditions.

Including Farmer Irrigation Behavior in a Sociohydrological Modeling Framework With Application in North India

Understanding water user behavior and its potential outcomes is important for the development of suitable water resource management options. Computational models are commonly used to assist water resource management decision making; however, while natural processes are increasingly well modeled, the inclusion of human behavior has lagged behind. Improved representation of irrigation water user behavior within models can provide more accurate and relevant information for irrigation management in the agricultural sector. This paper outlines a model that conceptualizes and proceduralizes observed farmer irrigation practices, highlighting impacts and interactions between the environment and behavior. It is developed using a bottom-up approach, informed through field experience and farmer interaction in the state of Uttar Pradesh, northern India. Observed processes and dynamics were translated into parsimonious algorithms, which represent field conditions and provide a tool for policy analysis and water management. The modeling framework is applied to four districts in Uttar Pradesh and used to evaluate the potential impact of changes in climate and irrigation behavior on water resources and farmer livelihood. Results suggest changes in water user behavior could have a greater impact on water resources, crop yields, and farmer income than changes in future climate. In addition, increased abstraction may be sustainable but its viability varies across the study region. By simulating the feedbacks and interactions between the behavior of water users, irrigation officials and agricultural practices, this work highlights the importance of directly including water user behavior in policy making and operational tools to achieve water and livelihood security.

A spatio-temporal land use and land cover reconstruction for India from 1960–2010

In recent decades India has undergone substantial land use/land cover change as a result of population growth and economic development. Historical land use/land cover maps are necessary to quantify the impact of change at global and regional scales, improve predictions about the quantity and location of future change and support planning decisions. Here, a regional land use change model driven by district-level inventory data is used to generate an annual time series of high-resolution gridded land use/land cover maps for the Indian subcontinent between 1960–2010. The allocation procedure is based on statistical analysis of the relationship between contemporary land use/land cover and various spatially explicit covariates. A comparison of the simulated map for 1985 against remotely-sensed land use/land cover maps for 1985 and 2005 reveals considerable discrepancy between the simulated and remote sensing maps, much of which arises due to differences in the amount of land use/land cover change between the inventory data and the remote sensing maps.

Adaptation of SuDS Modelling Complexity to End-Use Application

Sustainable urban Drainage Systems (SuDS) have gained popularity over the last two decades as an effective and optimal solution to continuous population growth and urban creep. SuDS do not only provide resilience towards pluvial flooding but they also provide multiple benefits ranging from amenity improvement to ecological and social well-being amelioration. To understand these complex interactions SuDS modelling is the tool to inform decision makers. Major developments in SuDS modelling techniques have been observed in the last decade, from simple lumped or conceptual models to very complex models. Several software packages have been developed to aid planning and implementation of SuDS. These often require extensive amount of data and calibration to reach acceptable level of accuracy. However, in many cases simple models may fulfill the aims of a particular stakeholder. Thus, it is very important to understand stakeholders’ priorities and aims and optimize the selection of modelling techniques according to the end-use application.

Developing a New Modelling Tool to Allocate Low Impact Development Practices in a Cost Optimized Method

Nowadays there is a need to overcome the effects caused by rapid urbanisation with more innovative methods. Recently, source control approaches, known as Low Impact Development (LID), are being used by urban planners to cope with water related problems and any other environmental issues due to their cost-effectiveness and reliability. To meet the needs of decision makers, the effects of these practices should be analysed at catchment scale. To do this, allocation of LID techniques in most suitable locations is essential. In this research a new modelling tool called LID locator is added to the WetSpa-Urban software package for more accurate placement of these techniques. The maximum area that can be covered by different types of LIDs are defined by finding the potential areas prone to generate runoff in combination with suitability maps calculated based on size limitation and implementation restriction for each LID measures. Then, the new cost-optimization tool is added through new procedure. This study is testified in the Watermaelbeek catchment situated in Brussels capital region.

Performance Evaluation of Retrofitted Low Impact Development Practices in Urban Environments: A Case Study from London, U.K.

Low impact development practices (LID), or what are known as Sustainable urban Drainage Systems (SuDS) in the UK, are expected to have a synergetic effect with the existing infrastructure to mitigate urban storm-water flooding. Designing and implementing effective LID practices require reliable full-scale data about their performance in different applications over an extended period of time; however, relatively few examples of LID practices have been monitored to provide such information. This study developed an innovative micro-monitoring system to assess the performance of porous pavement and rain gardens as retrofitting technologies in three streets within a Thames Water Utilities Limited pilot scheme implemented in London, UK. The system includes the installation of a V-notch weir at the outlet of each LID device to provide an accurate and reliable quantification of a wide range of discharges. In addition, a low flow sensor is installed downstream of the V-notch to validate the readings. Based on accurate pre-installation flow data from the study streets, extensive laboratory calibrations under different flows depicting the exact site conditions were performed prior to installing the devices in the field. The micro-monitoring system is well suited for highresolution temporal monitoring and enables accurate long-term evaluation of LID components’ performance. The equipment was installed in February 2017, and the monitoring will cover a period of 2 years.