What is a Hydrology Reports?

Introduction 

As you’d have guessed, hydrology has something to do with water. Besides, ‘hydro’ is a Greek word that refers to water. With that in mind, water is an important resource, since it’s essential for supporting life on earth. 

However, it plays a crucial role in civil engineering as well. For instance, engineers, architects, or planners involved in any development project have to consider the potential effect of floodwater on the site. Similarly, changes in land use may involve activities like deforestation, which can increase the chances of flooding or affect the water flow. 

Either way, this makes hydrology an area of interest in the civil engineering field. But what does it entail? And what is its importance in civil engineering?  

Read on to find out! 

What’s Hydrology? 

By definition, hydrology refers to the scientific study of circulation, distribution, movement, and properties of water on Earth. It entails water resources, environmental watershed sustainability, and the water cycle. 

That said, hydrology engineering involves applying the knowledge of this field for practical use. For instance, it may involve analysis, planning, operation, design, and construction of projects for the utilization, management, and control of water resources. 

In a land development project, hydrology usually refers to the water quantity, precipitation rate, and surface runoff rate as well as timing its arrival at the project site. 

Hydrological Cycle 

A hydrological cycle is a continuous process by which water moves from the ground surface to the atmosphere and back to water bodies and land. Therefore, any biological, chemical or physical process that involves transporting water beneath and over the earth’s surface is part of the water cycle. 

Water may take various pathways in its continuous cycle of returning to the atmosphere like falling as snow or rainfall. Also, it can fall into rivers, and finally to water bodies like oceans and seas. More notably, it can soak into the ground and be transpired by plants or evaporate directly as the soil surface dries. Alternatively, it can percolate through the soil surface to aquifers (groundwater reservoirs). Here, it will be stored or flow back to streams, wells, and springs by seepage. 

Major physical processes in the water cycle 

The global hydrological cycle can be classified into various components that form a continuous water movement. They include; 

• Evaporation 

This refers to the process in which water on the earth’s surface, either on water bodies or land, is turned into vapor form. As water changes from its liquid to a gaseous state, a considerable heat amount is exchanged. In most cases, that energy comes from solar radiation and other elements like vapor pressure and air temperature.  

• Transpiration 

Transpiration is the process by which growing plants absorb water in the soil and discharge it back to the atmosphere through their leaves. To be precise, leaves have little pores known as stomata, which aids in this process. 

• Evapotranspiration 

Basically, evapotranspiration is a combined process of transpiration and evaporation. Therefore, it’s simply a process that involves the discharge of water vapor to the atmosphere both from the vegetation and water sources. 

• Precipitation 

Precipitation is a process in which all and any form of water in the atmosphere falls to the ground. The most common forms of precipitation include; rain, drizzle, snow, and so on. Typically, 2 sub-processes cause the atmosphere to release precipitation. That is; the ice-crystal process and the coalescence process. 

Either way, the precipitated water may fall onto land or into a water body. Then it is dispersed into the water cycle in various ways. 

• Percolation 

Percolation is the movement of subsurface water in the soil layers to the water table through capillary forces and gravity. 

• Infiltration 

Infiltration is the physical process that involves water movement through the boundary area where the atmosphere meets the soil. In other words, it’s the movement of water into the underlying soil layers from the earth’s surface. Infiltrated water becomes subsurface runoff or stored for later evapotranspiration. 

• Surface Runoff

Surface runoff is the precipitated water and overland flow that flows to a river channel or stream through the ground surface. 

Hydrology in Civil Engineering 

Every development project changes how the water flows on the site. For instance, if you clear a land area, precipitated water will more likely run off the land instead of being absorbed by trees and grass. This newly created surface runoff can have a negative impact on the adjoining land parcels, especially if it’s not controlled. 

To address this issue, local development authorities require sites designs that meet specific water-related criteria. More notably, site designs that don’t negatively impact adjoining sites through increased surface runoff. 

At the same time, a civil engineer uses hydrology reports to show the anticipated changes in the flow of surface water due to the proposed site design. The main aim of these reports is to determine whether the post-development runoff is greater or equal to the pre-development surface runoff. 

Typical requirements in hydrologic design include runoff reduction and offering water quality treatment. This can be done through various storm events. Also, engineers use information related to soil type, land covers, drainage basin sizes, precipitation, and more to establish this data. Moreover, a drainage report is needed to support the runoff management plan for any proposed development project. 

After compiling the hydrology reports, engineers move on to design the hydraulic system of the stormwater system. This will help to manage any changes in water flow that results from the proposed project. 

Significance of hydrology reports in Civil engineering 

A hydrology report is important in civil engineering for various reasons. For instance; 

• It helps hydrologists and engineers establish the relation between underground water resources and surface water. 
• It’s essential for establishing the maximum flood a construction project, like a dam, can cause. 
• It allows engineers to determine the flow over different hydraulic structures like urban storm drainage systems, spillways, and highway culverts. 
• It determines the reservoir capacity that will ensure an adequate water supply for domestic, industrial, and other purposes. 
• Applications of engineering hydrology provide the nature of rainfall patterns, water flow, and more. 
• Lastly, hydrology is important for analyzing the on-site seepage and drainage condition before any engineering project commences. 

Final Word 

All things considered, hydrology plays an important role in a development project, especially in civil engineering structures. Therefore, hydrology reports are needed to help alert or reassure planners and developers regarding potential issues of concern. More importantly, this will help to establish effective strategies for controlling and reducing water flows resulting from the new project.