About hydrological planning

One of the most important tasks of hydrological planning is water resources to manage the (I think 'tasks' needs a verb - something that is 'done', so I suggest to 'manage' - otherwise you can change allocation/distribution into infinitives) allocation and distribution of water resources among different water uses. The main water uses in Spain are urban use, agricultural, industrial (not connected to the urban network), (make that 'not connected ...' parenthetical) and hydroelectric. Water resources are mainly (associate 'mainly' with 'rivers...' - not with 'found') found mainly in rivers, reservoirs and groundwater. Due to the fact that Spain is mainly dry/aridity of Spain, nowadays it is really difficult nowadays to supply/satisfy/meet all the water demands from different uses and, at the same time, to satisfy/achieve the environmental objectives of the European Water Framework Directive (2000/60/EC). Thus, the allocation of water resources allocation is done using balances between involves balancing water resources and water demands, taking into account the priorities and management rules of water demands, the operation rules of infrastructures (dams, pipes and so on) and the environmental objectives. (ok, complex phrases, but pretty good! the commas sentence length are problematic) These water balances are done by achieved via simulations of in a mathematical model that includes all the necessary data.

About hydrological planning

One of the most important tasks of hydrological planning is water resources allocation and distribution among different the water consumers. uses. The main water consumers uses in Spain are urban use, agricultural, industrial not connected to the urban network and hydroelectric. Water resources are mainly found in rivers, reservoirs and groundwater. Due to the fact that Spain is mainly dry, nowadays it is really difficult to supply comply with all the water demands from the  different uses sectors and, at the same time, to satisfy the environmental objectives of the European Water Framework Directive (2000/60/EC). Thus, water resources allocation is done using balances between water resources and water demands, taking into account the priorities and management rules of water demands, the operation rules of infrastructures (dams, pipes and so on) and the environmental objectives. These water balances are done by simulations of a mathematical model that includes all the necessary data.

About hydrological planning

One of the most important tasks of hydrological planning is water resources allocation and distribution among different water uses. The main water uses in Spain are is to serve urban areas use, agricultural needs, industrial systems not connected to the urban network and hydroelectric systems. Water resources are mainly found in rivers, reservoirs and groundwater. Due to the fact that Spain is mainly dry, nowadays it is really difficult to supply all the water demands from for different uses and, at the same time, to satisfy the environmental objectives of the European Water Framework Directive (2000/60/EC). Thus, water resources allocation is done using balances between water resources and water demands. This process takes taking into account the priorities and management rules of water demands, the operation rules of infrastructures (dams, pipes and so on) and the environmental objectives. These water balances are done by simulations of a mathematical model that includes all the necessary data.