干旱期间陆地水储量骤减会造成复杂而显著的地表形变。随着空间大地测量技术的快速发展，GNSS获得的高时空分辨率地表形变信息为水文干旱监测提供了全新视角。本项目以获得精度高、适用性强的GNSS垂向形变水文干旱指数（GNSSVD-HDI）为目标，基于我国“陆态网”数据，针对水文负荷形变信号提取及短序列GNSSVD-HDI构建两个关键科学问题开展研究。主要内容包括：以先验水文观测为约束，研究形变对水文过程的响应机制，建立噪声滤波与非水文负荷形变主要信号分离的客观准则，精确提取站点水文负荷形变；探究水文负荷形变的气候响应特征，建立短序列GNSSVD-HDI精细分区构建模型，获得适用于不同气候类型的高精度水文干旱指数，并评价其有效性。该项目构建的GNSSVD-HDI不仅能反映地表和地下水的综合变化，而且具有较高的时间分辨率、空间覆盖度和适用性，为我国水文干旱监测与预报预警提供新的数据和科学依据。

Abrupt terrestrial water storage deficits during drought can cause complex and significant crustal deformations. With the rapid development of space geodesy, high spatial and temporal resolution of crustal deformations observed by GNSS provide a new perspective for hydrological drought monitoring. In this project, a GNSS vertical deformation-derived hydrological drought index (GNSSVD-HDI) with high precision and applicability is proposed based on the data from Crustal Movement Observation Network of China (CMONOC), by considering two key scientific issues on the signal extraction of hydrological loading deflections and the construction of short record-based GNSSVD-HDI. The main contents are: using in-situ hydrological observations as the prior knowledge to study the response mechanism of deformation to hydrological process, and an objective criterion for noise filtering and removing the main deformation signal induced by non-hydrological loadings is built to extract hydrological displacements precisely at GNSS sites. Then, exploring the response characteristics of hydrological loading deformations at various climate settings, and a specific refined model based on short GNSS records is designed to obtain accurate hydrological drought index data at different climate regions. Finally, the feasibility of the proposed drought index is verified. The GNSSVD-HDI index in this project not only can reflect surface and subsurface water changes, but also has a relative higher temporal resolution, spatial coverage and applicability. The research results provide new data and scientific basis for hydrological drought monitoring, forecasting and early warning in our country.