Topic-5-Watershed

The RETURN PERIOD is a statistical concept used to estimate how often a particular level of rainfall is expected to occur, often expressed in years.

These return periods are used to estimate the expected rainfall amounts that can be anticipated to occur once in those respective time frames, helping in flood risk assessment and planning.

The order number (m) is the rank assigned to each item (such as rainfall or flowrate) when arranged in descending order for the purpose of calculating the return period.

The RETURN PERIOD is used to assess and manage the risk of extreme weather events like heavy rainfall and flooding.

The calculation of the expected flood discharge that has a 0.1% chance of being equaled or exceeded in any given year.

Overtopping refers to the situation where floodwaters exceed the height of a dam, leading to potential failure and significant downstream impacts.

It is one of the most widely used probability distribution functions for extreme values in hydrologic and meteorologic studies for predicting flood peaks and maximum rainfall.

The 10-yr flood is a design standard used to assess the risk of flooding, indicating that there is a 10% chance of this level of flooding occurring in any given year.

A watershed is an area of land where all the water that falls within it drains into a common outlet, such as a river, lake, or ocean.

Flood discharge estimation for a 1000-year return period refers to the calculation of the expected maximum discharge of a river or stream that has a 0.1% chance of being equaled or exceeded in any given year.

Kz is a frequency factor obtained from a table, used in calculations related to return periods.

The calculation of the expected flood discharge that has a 0.5% chance of being equaled or exceeded in any given year.

Designing for floods below the maximum possible implies accepting a certain level of risk, as failures can occur even when structures are designed for significant flood events.

Computations in Frequency and Duration Studies involve statistical analyses to determine the likelihood and duration of specific hydrological events, such as rainfall or flooding.

Flood discharge estimation for a 100-year return period refers to the calculation of the expected maximum discharge of a river or stream that has a 1% chance of being equaled or exceeded in any given year.

Watersheds in the Philippines are crucial for managing water resources, supporting biodiversity, and mitigating flood risks, especially in a country prone to tropical storms.

Watershed Management is the process of planning and implementing practices to manage the use and development of land and water resources in a watershed to achieve specific environmental, economic, and social objectives.

Frequency and Duration Studies are analyses that assess the occurrence and length of specific hydrological events, such as rainfall or flooding, over a given period.

Rainfall for different return periods can be estimated using statistical methods such as frequency analysis, which involves analyzing historical rainfall data to predict future events.

The variates (flowrates, rainfall, etc.) are transformed into logarithmic form (z) to analyze the transformed data.

The RETURN PERIOD provides an estimate of the average time between events of a certain magnitude.

The calculation of the expected flood discharge that has a 1% chance of being equaled or exceeded in any given year.

The return period is the estimated time interval between events of a certain magnitude, often used to predict the likelihood of a specific rainfall amount occurring in a given year.

zt is the logarithmic form of xt, which is the antilog of zt for a specific return period.

Calculated risk in flood design refers to the assessment of potential flood events and their impacts, balancing safety and economic considerations when designing structures.

Frequency and Duration Studies are analyses that assess the occurrence and length of specific hydrological events over a defined period, often used to evaluate rainfall patterns and their implications for water resource management.

The return period (Tr) is a statistical measure used to estimate the average time interval between events of a certain intensity or greater, calculated using the formula Tr = (n + 1) / m, where m is the order number and n is the number of years.

Cs = Nσz - zave^3 / (N - 1)(N - 2)σz^3, used for determining Kz.

'n' represents the number of years of data used in the return period calculation.

Frequency and Duration Studies analyze the occurrence and length of rainfall events over a specified period to understand their patterns and impacts.

z = log x, which expresses x in terms of its logarithm.

Arranging items in descending order is crucial for determining their rank, which is necessary for accurately computing the return period.

A 180-year rainfall event refers to a significant rainfall occurrence that is statistically expected to happen once every 180 years, indicating its rarity and intensity.

Flood discharge estimation for a 200-year return period refers to the calculation of the expected maximum discharge of a river or stream that has a 0.5% chance of being equaled or exceeded in any given year.

σz = (σz - zave^2) / (N - 1), where σz is the standard deviation and N is the number of observations.