CE 515 M1HYDRO METEOROLOGICAL DATA ANALYSIS

Hydro-meteorology is the scientific study of the interaction between meteorological and hydrologic phenomena, including the occurrence, motion, and changes of state of atmospheric water, and the land surface and subsurface phases of the hydrologic cycle. Hydrometeorologic studies address questions regarding land use, the long-term effects of climate change on water resources, and regional precipitation.

DEFINITION OF TERMS: Rainfall the quantity of rain falling within a given area in a given timeAtmospheric and water temperature - the degree or intensity of heat present inthe atmosphere and in a water resourcesEvaporation is a process by which water changes from a liquid to a gas Humidity - is the amount of water vapor in the airWind speed - or wind flow velocity, is a fundamental atmospheric rate and it is caused by air moving from high pressure to low pressure, usually due to changes in temperatureHours of sunshine - is a climatological indicator, measuring duration of sunshine in given period (usually, a day or a year) for a given location on Earth River levels and flows - the current depth and discharge of water of river in a given timeSediment concentration levels theratioofthedryweightofthesedimentinawater sedimentmixture(obtainedfromastreamorotherbodyofwater)tothetotalweightofthe mixture

HYDRO METEOROLOGICAL DATA ANALYSIS includes continuous built up of rainfall statistics at various temporal and spatial scales, hydro-meteorological studies for different river catchment with a view to estimate Standard Project Storm (SPS), probable Maximum precipitation (PMP), Time distribution of rainfall storm, Intensity-frequency Analysis of rainfall which is used by design engineers for construction of Dams, railways and road bridges, culverts etc. for different central and state organizations.

*RAINFALL STATISTICS

The rainfall events were classified into four types according to the definition put forth by Huff determining the quantities precipitated during the four quartiles of duration. The rainfall is categorized by the duration that has the greatest precipitation: rainfall is classified as type I if most of the rainfall occurs in the first 25% of the total duration; as type II if most of the rainfall occurs between 25 and 50% of its duration; as type III if most of the rainfall occurs between 50 and 75% of its duration; and as type IV if most of the rainfall occurs in the last 25% of its total duration. Rainfall characterization is significant for many types of hydrological studies, mainly for those that aim to estimate flow volume and peak discharge of surface runoff and erosion losses.

*HYDRO-METEOROLOGICAL STUDIES FOR DIFFERENT RIVER CATCHMENT

Estimation sites and data

Spatial interpolation of observed records

Estimating flow duration curves for environmental flow sites

Generating continuous stream flow time series

*PROBABLE MAXIMUM PRECIPITATION

One informational product used for planning, probable maximum precipitation (PMP), is defined as the greatest accumulation of precipitation for a given duration meteorologically possible for a design watershed or a given storm area at a particular location at a particular time of year. Climate change effects on PMP are analyzed, in particular, maximization of moisture and persistent upward motion, using both climate model simulations and conceptual models of relevant meteorological systems. Climate model simulations indicate a substantial future increase in mean and maximum water vapor concentrations. PMP values are, in principle, most dependent upon atmospheric moisture, and transport of moisture into storms, persistent upward motion, and strong winds where orographic uplift is important.

a. Convergence and vertical motionb. Atmospheric water vaporc. Physical synthesis: Linking PMP and atmospheric water vaporA principal application for PMP values is the design of infrastructure for water retention (dams) or routing, where failure would be catastrophic.

*TIME DISTRIBUTION OF RAINFALL STORM

In the definition of superficial storm drainage, rainfall intensity and area relationships, intensity, duration and frequency (IDF) relationships, as well as rainfall distribution during an event, called the rainfall time distribution, must be considered.The time distributions may be expressed as cumulative percentages of storm rainfall and storm duration to enable valid comparisons between storms and to simplify analyses and presentation of data. Information also might be presented in the form of families of curves derived for groups of storms categorized by quartile storms depending on whether. For most design applications, it is recommended using the quartile type occurring most often for the design duration under consideration.

*INTENSITY-FREQUENCY ANALYSIS OF RAINFALL

Rainfall intensitydurationfrequency IDF curves are graphical representations of the amount of water that falls within a given period of time in catchment areas. It is a mathematical relationship between the rainfall intensity i, the duration d, and the return period T. Indeed the IDF-curves allow for the estimation of the return period of an observed rainfall event or conversely of the rainfall amount corresponding to a given return period for different aggregation times. Rainfall Intensity (mm/hr), Rainfall Duration (how many hours it rained at that intensity) and Rainfall Frequency (how often that rain storm repeats itself) are the parameters that make up the axes of the graph of IDF curve. An IDF curve is created with long term rainfall records collected at a rainfall monitoring station. Ill get into the details of how to create an IDF curve and how much data you need in a future post, but needless to say, you need a lot of data. And the more data you have, the more accurate your curve will be.

SUBJECTS OF HYDRO-METEOROLOGICAL DATA ANALYSIS: 1. Hydrometeorological Hazards are hazards as result of natural processes or phenomena of atmospheric, hydrological or oceanographic nature such as:a. Floods - among the most frequent and costly natural disasters. Conditions that cause floods include heavy or steady rain for several hours or days that saturate the ground. Common types of floods include flash floods, river floods and coastal flood.b. Drought - an extended time when a region receives a deficiency in itswater supply, whether atmospheric,surfaceorground water. The impacts of drought are generally categorized as economic, environmental, and social.c. Tropical cyclones - are intense low pressure areas of the earth atmosphere coupled system and are extreme weather events of the tropics. They develop over large bodies of warm water, and lose their strength if they move over land. This is the reason for coastal regions receiving a significant damage from a tropical cyclone, while inland regions are relatively safe from their effect. Heavy rains, however, can produce significant flooding inland, and storm surges can produce extensive coastal flooding up to 40 kilometres from the coastline. Although their effects on human populations can be devastating, tropical cyclones can also relieve drought conditions. 2. Basin - wise water resource project development. The total land area that contributes water to a river is called a watershed, also called differently as the catchment, river basin, drainage basin, or simply a basin. 3. Water resources projects such as dams and reservoirs

MODERNIZATION OF HYDROMETEOROLOGICAL DATA ANALYSIS: All countries are continually challenged by the effects of weather and its influences on economic stability, national commerce and growth. While significant weather events are unavoidable, the impacts of significant weather can be significantly mitigated through the implementation of modern hydro-meteorological monitoring, prediction, and warning systems. Every country faces a unique mix of hydro-meteorological and environmental challenges which have significant impact on the economic and social well-being of the population. To better support the needs of decision makers, all countries must modernize their environmental monitoring systems, hydro-meteorological analysis and prediction tools, and dissemination methods to better protect life and property, and advance public and private economic interests nationwide. HYDROMETEOROLOGICAL MONITORING NETWORKS Multi-sensor hydro-meteorological monitoring networks, composed of gauge, radar and satellite sensors collect rainfall, temperature, and other data that are used by forecasting models to produce flash flood guidance and threat information. Hydro-meteorological monitoring networks and associated communications are critical to the success of any flash flood early warning system. Hydro- meteorological sensors for flash flood forecasting. These include rain gauges, river/stream flow gauges, radars, and satellites Communications requirements for collecting sensor data Backup communications for collecting data and distributing warnings by local/provincial forecast offices and National Meteorological and Hydrological Service (NMHS) centers International Data Observation and Information Collection, including the role of the Global Telecommunications System (GTS)

HYDROMETEOROLOGICAL DATA QUALITY CONTROL No hydrology program can be successful if the underlying data is inaccurate. The quality of the data directly affects the quality of the hydro-meteorological guidance, forecasts and warnings.

What needs to be done? The following tasks need to be done in order to monitor and quality control data. Procedures need to be developed, automatic or manual, to ensure that these duties are performed: Make sure data is coming in. If it isn't, find out why. If applicable, notify appropriate person, or agency of the problem. Look for data that is obviously wrong. For example, readings that are off by orders of magnitude, or outside an acceptable range of values, big jumps in values for no reason, etc.. Change data if correct value is known, or if a reasonable estimate can be made, otherwise replace bad Data with a symbol that denotes missing. Look for erroneous zeros.