Water resources engineering is the branch of engineering that deals with the planning, design, construction, operation, management and maintenance of water resources infrastructure systems. These systems include among others dams and reservoirs, groundwater wells, river diversion weirs and barrages, canals and pipe systems to store and transport water for drinking, irrigation, hydropower, and other purposes. Water resources engineers also analyze climate variability and changes as well as forecast hydrological extremes like floods and drought, monitor water quality and pollution control. Water resources engineers use their knowledge of hydrology, hydraulics, irrigation, and other engineering principles to design, implement and manage water resource infrastructural systems for developmental uses and sustainable ecosystem services. They also use computer modeling and other modern tools to simulate and analyze the occurrence and distribution of water resources both in time and space.

More specifically, a water resources engineer work on:

• Designing and supervision of building dams and canals to store and distribute water
• Design, develop, and manage water supply, water treatment, and wastewater treatment systems.
• Designing and supervise building of flood control and drainage systems
• Protecting water resources from pollution
• Managing water resources in response to climate change