15.3 By 2030, combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradation-neutral world

Introduction

In recent decades, many regions of the world have experienced a growing instability in rainfall patterns. What were once predictable seasonal rains have become unpredictable —arriving late, falling too fast, or not coming at all. As communities face longer droughts, more frequent floods, and declining snowpack, it’s increasingly clear that these disruptions are not isolated events, but signals of a deeper transformation: the global water cycle is changing.

Since ancient times, people have established communities in river deltas because it provides water, fertile land, and transportation access, making them an ideal place to live. This pattern has been carried forward to the present. With nearly 6 billion people living in river deltas, they are one of the most densely populated places on Earth (Kuenzer and Renaud, 2011). However, they are facing threats such as climate change, sea level rise, land use changes, and ecosystem degradation.

When rain falls on Earth, the water starts moving and flowing downhill through sewers and rivers as runoff. Runoff is extremely important to recharge surface water bodies and groundwater. Furthermore, runoff changes the landscape by action of erosion. It is an integral part of the water cycle (Earth Science Data Systems 2021). 

Translated by Isabel Zetina

Cuando la lluvia cae sobre la Tierra, el agua empieza a moverse y a fluir cuesta abajo a través de alcantarillas y ríos en forma de escorrentía. La escorrentía es extremadamente importante para recargar las masas de agua de la superficie y las aguas subterráneas. Además, la escorrentía modifica el paisaje por acción de la erosión. Es una parte integral del ciclo del agua (Earth Science Data Systems 2021).