Water management involves balancing the use of surface and underground water with land needs, irrigation demands, and pollution control. By analyzing annual water balances, we can determine how much water an area can use in a typical year. Adjusting land use can help match water use with available resources. Monitoring salt levels in water is crucial, along with tracking changes in the water table and pollution levels. Despite potential errors in data, accurate management decisions can still be made as long as measurements are consistent. Using redundant data can improve accuracy and provide extra information for monitoring purposes.