An improved moisture and wind maximization method for probable maximum precipitation estimation and its application to a small catchment in China

Abstract

The probable maximum flood (PMF) is the highest design criterion for major hydraulic projects whose failure might cause severe loss of life and property. The probable maximum precipitation (PMP) is the corresponding extreme design rainfall, which is defined as the theoretically greatest depth of precipitation for a given duration over a particular area under modern meteorological conditions. The moisture and wind maximization (MWM) method is widely used in deriving 24‐hr PMP. However, variables in MWM factor (e.g., maximum precipitable water and wind speed) are collected from full study durations regardless of their respective main moisture inflow directions in each year. This issue could lead to higher PMP estimates which could lead to costs in the construction of hydraulic structures. To alleviate this possible problem, an improved moisture and wind maximization (IMWM) approach is proposed based on the concept of a “wind rose diagram”, data (e.g., rainfall, wind speed, dew point) are grouped according to the main moisture inflow directions of a study catchment. Analysis shows the IMWM approach has the potential to provide lower PMPs, which would have economic implications for hydraulic designs. The storm transposition approach is applied for safety, extraordinary storms occurring in the homogeneous rainfall region are transposed to a study catchment after being maximized by the IMWM method. In addition, statistical methods, including storm formulation, trend analysis and hydrological frequency analysis, are used for deriving short‐duration PMPs. The Nash instantaneous unit hydrograph coupled with regional empirical formulas is then applied to estimate PMFs. As an example, PMP/PMF estimation approaches are applied to an important flood control project located in a small ungauged catchment of China. The study can provide a scientific basis for the construction of the study project as well as a reference for similar high‐hazard projects.

Variation and attribution of probable maximum precipitation of China using a high-resolution dataset in a changing climate

“…This fact suggests more justification should be made by comparing it with previous research. A few regional studies have calculated 1 d PMP over different parts of China (Svensson and Rakhecha, 1998;Yang et al, 2018;Zhou et al, 2020). For example, Svensson and Rakhecha (1998) used the moisture maximization factor to estimate PMP over the Hongru River basin of the Huaihe River basin in eastern China, with a result of 460 mm d −1 that is generally within the range of our 1 km PMP map of the corresponding area (200-600 mm d −1 , Fig.…”

“…2c). Zhou et al (2020) applied the storm transposition method to estimate PMP for a small ungauged catchment in northern China from 118°20 -118°26 E and 40°26 -40°30 N. The results change from 397 to 570 mm d −1 at most of the stations, with an extreme value of 1026 mm d −1 in Zhangmu, Hebei Province (see Fig. 1c).…”

An observational view of rainfall characteristics and evaluation of ERA5 diurnal cycle in the Yarlung Tsangbo Grand Canyon, China

“…TCWV at Lulang is the lowest of the three sites, which may be because water vapor is released as it climbs along the YGC. Precipitation that falls on a windward slope is usually greater than that on a leeward slope (Zhou et al ., 2020). This explains why Lulang and Danka have an annual precipitation of ∼800 mm (Table 1), which is much lower than at the other sites.…”