Preface

Well over 40% of the world's population is affected by water scarcity. The World Bank works with the majority of nations to ensure that water use is sustainable, that climate resilience is built, and that integrated management is strengthened. Some countries are currently putting an unprecedented amount of strain on their water supplies. Water exists in various forms, such as lakes and rivers, glaciers and ice sheets, oceans and seas, subversive aquifers, and fog in air and clouds. The water cycle refers to how water enters and leaves the atmosphere; it evaporates from the Earth's surface and falls back as precipitation. Like waterfalls, it accumulates in bodies of water and replenishes the groundwater level.

The world's population is rapidly growing with forecasts estimating that, if current systems continue, the Earth will confront a 40% gap between estimated demand and accessible water supply by 2030. Recurring water scarcity, hydrological unpredictability, and extreme weather events (floods and droughts) are significant global prosperity and stability challenges. The importance of water scarcity and drought in exacerbating fragility and conflict is becoming better recognized.

By 2050, providing for nine billion individuals will demand a 60% increase in food production (which presently uses 70% of the resource) and a 15% increase in water extraction. Separately from this increasing demand, water is at present in short supply in many world regions. According to statistics, 40% of the world's population lives in water-scarce regions, and this dilemma affects about 14% of global GDP. By 2025, around 1.8 billion individuals will be living in water-scarce areas or countries. For several nations today, water security is a critical issue.

Climate change will aggravate conditions through changing hydrological cycles, resulting in inconsistent global water supplies, while floods and droughts are expected to be more frequent, erratic, and intense. These events will put roughly one billion residents in monsoonal basins and 500 million in deltas at serious risk. Historically, an estimated \$120 billion per year is accrued just from property damage. Droughts pose potential subsistence limitations to poor countryside demographics, which are at the mercy of unpredictable rainfall.

The fragmentation of water further hampers water security. A total of 276 transboundary basins are divided by 148 nations, accounting for 60% of the world's freshwater flow. From this, 300 aquifer systems are transboundary, meaning around two billion people depend on global groundwater. Fragmentation concerns are commonly mirrored at the national level, requiring teamwork to ensure adequate water resource management and development schemes for all riparian areas. Nations will need to enhance the way they manage their water resources and related components to handle these complex and interrelated water concerns.

Investors will need to invest in institutional consolidation, information management, and (natural and non-natural) infrastructure development to increase water security in the face of rising demand, water scarcity, growing unpredictability, more significant extremes, and fragmentation concerns. Institutional mechanisms such as legal

and supervisory frameworks, water valuing, and incentives are mandatory to better allocate, control, and conserve water resources. Resource monitoring, decisionmaking under uncertainty, systems analyses, hydro-meteorological forecasting, and cautionary involvement of information systems. Savings in innovative technologies to improve productivity, keep and protect resources, reprocess stormwater and wastewater or groundwater, and develop alternative water resources ought to be explored to identify prospects to improve water storage. Ensuring swift dissemination and suitable adaptation or presentation of these advances will be critical to strengthening worldwide water security. Furthermore, innovative systems to improve water storage, including enrichment and reclamation of aquifers, should be explored to increase productivity, conserve and protect resources, reuse natural and wastewater, and take advantage of unconventional water sources. Rapid and appropriate adaptation of these advances is imperative to ensure global water security.

Healthy water management solutions for multifaceted water issues comprise unconventional knowledge and innovations integrated into water projects to intensify the impact. To this end, techniques operated in the spatial domain have the potential to successfully extract information about groundwater management and resources.

This book addresses the issues mentioned here in three sections:


This book asserts that platforms, sensors, data, techniques, and applications are all interconnected and work in tandem. While organizing the chapters according to their major goals, we also recognize that the authors of each chapter convey a complete story, at times ranging from the introduction of a method to a detailed application.

> **Bahareh Kalantar** RIKEN Center for Advanced Intelligence Project, Goal-Oriented Technology Research Group, Disaster Resilience Science Team, Tokyo, Japan

Section 1 Introduction
