DiHPS - A Distributed Heat Pulse Sensor Network for the quantification of subsurface heat and water fluxes

我们建议开发一种新型的分布式土壤水分和温度监测网络，该网络将从目前可用的监测技术（往往基于在时间和空间上孤立的点收集数据）向实时监测技术迈进，空间上-分布式数据收集，使有效和响应决策，以应对迅速增长的需求在不断变化的气候。拟议的系统将基于将分布式温度传感器（Distributed Temperature Sensor，简称感温传感器）技术与主动热源相结合。所谓的主动加热（A-A）允许沿着主动加热的电缆观察与流动相关的加热和冷却模式。正是这种分布式热脉冲，我们将在拟议的传感器网络- DiHPS的发展中使用的A-ESTA技术。虽然DiHPS在热通量和水通量评估方面的应用将更加广泛，但在本项目中，我们将重点展示其对量化土壤水分含量和热特性的适用性。这些土壤参数的时空分布/动态描述对于许多农业，工程和气象应用都很重要。例如，土壤湿度是控制陆地-大气相互作用的关键状态变量，也是水文系统变化的早期指标，例如与每日蒸散或基于事件的补给周期或极端事件（即，干旱或洪水）。它广泛用于农业（例如，灌溉管理）、林业（如种植园需水量估计）、气象学（如当地和区域天气预报）、水资源管理（如地下水补给估计）以及干旱/洪水预警系统中的状态指标变量。土壤热特性影响着地下和地表能量的分配，并与土壤温度、地下水和热量的运动及其在地表的传递有关。由于这些原因，土壤物理学家，作物科学家和微气象学家研究热特性，它们在工程应用中也很重要，（例如，确定埋地电缆的额定电流，地热交换器设计）。我们将建立在早期的工作，这已经证明了主要能力的A-EQUIPMENT测量土壤水分在受控条件下的蒸渗设施。我们将把这项技术从单点应用扩展到分布式的、真实的时间传感器网络和一个盘绕的、垂直的A型剖面仪，用于以高的空间和时间分辨率测量土壤水分含量和热特性。该网络和分析器将在TRL 4进行测试，安装在伯明翰林业研究所（BIFoR）的测试站点。结果将进行比较，在现场的土壤水分含量和热性能数据从频域反射（FDR）土壤水分探头和热针探针测量，分别。为了实现实时、自主的系统操作，将测试一组加热策略，并定义初始阈值（触发值）。这些将定义在土壤温度发生什么变化时，如在非主动模式下通过连续温度观察所观察到的，将触发主动模式的启动/停止。DiHPS的一个关键组成部分是实时控制触发从主动到被动观测模式的变化。这将需要在逆向建模和渐近方法的基础上开发一套算法，能够实时处理原始数据，以提供所需的产出。没有现有的DTS应用程序试图提供如此详细和实时的温度或土壤湿度数据。如果成功的话，我们预计将在预警系统或提供详细的过程理解等方面对使用过程的方式进行一步改变。

We propose the development of a novel, distributed soil moisture and temperature monitoring network that will present a step change from currently available monitoring technologies, which tend to be based on data collection at isolated points in time and space, to real-time, spatially-distributed data collection that enable effective and responsive decision making to deal with rapidly increasing demands in a changing climate.The proposed system will be based on combining Distributed Temperature Sensor (DTS) technology with an active heat source. The so-called Active DTS (A-DTS) allows observing flow-related heating and cooling patterns along the actively heated cable. It is this Distributed Heat Pulse, A-DTS technology that we will use in the development of the proposed Sensor network - DiHPS. While broader applications in heat and water flux assessments will be possible with DiHPS, in this project we will focus on demonstrating its suitability to quantify the moisture content and thermal properties of the soil.Description of the spatial and temporal distribution/ dynamics of these soil parameters is important for many agricultural, engineering and meteorological applications. Soil moisture, for example, is a key state variable in controlling land-atmosphere interactions and an early indicator of changes in the hydrological system, e.g. associated with daily evapotranspiration or event-based recharge cycles or with extreme events (i.e., droughts or floods). It is widely used in agriculture (e.g., irrigation management), forestry (e.g. plantation water demand estimations), meteorology (e.g. local and regional weather forecasts), water resources management (e.g. estimation of groundwater recharge) as well as a state indicator variable in drought / flood early warning systems. Soil thermal properties influence the partitioning of energy within the ground and at the ground surface, and are related to soil temperature and the movement of heat and water within the ground and their transfer across the ground surface. For these reasons, soil physicists, crop scientists and micrometeorologists study thermal properties, and they are also important in engineering applications, (e.g., determining the electric current rating of buried cables, ground heat exchanger design). We will build on earlier work which has demonstrated the principal capacity of A-DTS to measure soil moisture under controlled conditions in a lysimeter facility. We will expand this technology from a single point application to a distributed, real time sensor network and a coiled, vertical A-DTS profiler for measuring soil moisture content and thermal properties at high spatial and temporal resolution. The network and profiler will be tested at TRL4 by installing it at our test site at the Birmingham Institute for Forestry Research (BIFoR). The results will be compared with in-situ soil moisture content and thermal property data from Frequency-Domain Reflectometry (FDR) soil moisture probes and thermal needle probe measurements, respectively. To achieve real-time, autonomous system operation, a set of heating strategies will be tested and initial threshold (trigger values) will be defined. These will define at what change in soil temperature, as observed by continuous temperature observation in DTS passive mode, initiation/cessation of the DTS active mode will be triggered. A key component of DiHPS is the real-time control for triggering the change from active to passive observation mode. This will require the development of a set of algorithms, based on inverse modelling and asymptotic approaches, which can process the raw DTS data in real-time to provide the required outputs. No existing DTS-application attempts to provide temperature or soil moisture data temperature in such detail and in real-time. If successful, we anticipate a step change in the way DTS is employed, e.g. in early warning systems or for providing detailed process understanding.