Hydrology-phosphorus interactions under changing climate and land-use: overcoming uncertainties and challenges for prediction to 2050 (Nutcat 2050)

该提案旨在利用英国可用的最新数据和建模方法，在2050年之前的气候和土地利用变化情景下，推进我们对英国源头流域水文和养分转移之间相互作用的理解和预测。研究的集水区将是英国示范试验集水区，目标将通过以下方式实现：(1)利用现有的气候模式情景来设定变化的基线结果；(2)以DTC为重点的本地化利益攸关方激发讲习班，以制定针对气候情景的土地利用变化情景；(3)模拟当前的水文事件和未来流域水文变化，以应对气候/土地利用的变化；(4)利用来自示范试验集水区的实验和新获得的高分辨率观测，为模型的开发提供信息，从而对极端水文条件下的磷(P)行为有新的理解；(5)改进对未来P行为情景的预测(具有不确定性)，这源于对水文学-P相互作用的新理解；(6)尝试将信息从源头-集水区扩大到整个流域范围，以及；(7)将模型性能与现有P模型进行比较，并评估这一过程中涉及的不确定性，并进一步反复征求利益攸关方的意见。我们将重点放在10平方公里的尺度上，因为这与我们选择的研究区域--Defra DTC(来自伊甸园、Wensum和Avon DTC)的九个研究流域的大小一致；这个尺度也代表了沿着动员-交付-河流影响‘转移连续体’研究过程的理想规模。这些综合研究将产生营养通量的原型定量评估和预测。我们的假设是，风暴模式(更极端的事件，更长的干旱时期)的季节性变化增加，再加上与土地利用变化的相互作用，将极大地改变未来陆地-水连续体的溶解和颗粒磷通量，以及随后在河流和下游的滞留富营养化风险。我们将把我们最初的“基于系统证据的评估方法(SEBAM)”研究扩展到一个原型建模框架，该框架包括预测英国源头流域的磷通量的来源、动员、输送和溪流处理功能，并考虑土地利用变化，并使用该框架(结合该团队参与的其他项目的知识)扩大我们的信息，以确定在全流域规模预测其他营养行为的潜力。我们将利用九个Defra DTC子流域开始出现的新的、独特的高质量、高时间分辨率的P监测数据。这项工作的一个独特和令人兴奋的方面是使用专家启发程序，其中包括基于模糊不确定性的分析，为9个DTC Focus流域的每一种独特的景观类型制定量身定做的土地使用情景(以英国土地使用展望倡议为基础)。将这些信息与英国最新的气候情景结合起来，我们将包括高分辨率数值天气预报的新发展。然后，我们将利用这些情景研究到2050年气候和土地利用变化对水文、磷动员、输送和河流处理的影响，从新的经验学习和实验中了解到这一点。然后，将使用相关项目和我们的合作伙伴的数据，验证模型输出是否适用于更广泛的英国其他流域(Conwy、Ribble、Tarland)。在整个项目中，结果将与利益相关者一起进行测试。这将提供一个当地拥有的基于知识的框架，用于理解和管理未来来自农村集水区系统的养分转移，以及一些关于磷转移的令人兴奋的新科学。

The proposal aims to advance our understanding and predictions of interactions between hydrology and nutrient transfers in headwater catchments in the UK, under climate and land use change scenarios to 2050, using the very latest data and modeling approaches available for the UK. The study catchments will be the UK Demonstration Test Catchments (DTCs) and the aims will be achieved through: (1) using existing climate model scenarios to set baseline outcomes for change; (2) localized DTC-focused stakeholder elicitation workshops to develop scenarios for land use changes in response to the climate scenarios; (3) simulating current hydrological events and future changes in catchment hydrology in response to changing climate/land use; (4) new understanding of phosphorus (P) behaviour in extreme hydrological conditions, using experiments and newly available high resolution observations from the DTCs to inform model development; (5) improved prediction (with uncertainty) of future P behaviour scenarios arising from the new understanding of hydrology-P interactions; (6) attempting to scale up the information from headwater-catchment to full basin scale, and; (7) compare model performance with existing P models and assess uncertainties involved in this process, with further iterations of stakeholder consultation. We shall focus on the 10 km2 scale because this matches the size of the nine study catchments of the Defra DTCs (from the Eden, Wensum and Avon DTCs), which are our chosen study areas; this scale also represents the ideal size for studying processes along the mobilisation-delivery-in-stream impact 'transfer continuum'. These integrated studies will produce a prototype quantitative assessment and prediction of nutrient fluxes. Our hypothesis is that increased seasonal variability in storm patterns (more extreme events, long drought periods), combined with interactions with land use change, will greatly alter future dissolved and particulate P fluxes across the land-water continuum and subsequent retention in-stream and downstream eutrophication risk. We shall extend our initial 'Systems Evidence Based Assessment Methodology (SEBAM)' study that focused on mobilization of P at the farm scale (recently published by the team), into a prototype modeling framework that includes source, mobilization, delivery and in-stream processing functions for predicting P fluxes from UK headwater catchments, and considers land use change, and use this framework (combined with knowledge from other projects involving the team) to scale up our information to define the potential for predicting other nutrient behaviours at the full basin scale. We will capitalize on the new and unique high quality, high temporal resolution P monitoring data that is starting to emerge from the nine Defra DTC sub-catchments. A unique and exciting aspect of the work will be the use of expert elicitation procedures that incorporate fuzzy uncertainty-based analyses to develop tailored land use scenarios (building on the UK Land Use Foresight Initiative) for each of the unique landscape typologies for the 9 DTC focus catchments. Combining this information with the latest climate scenarios for the UK, we will include new developments in high-resolution numerical weather prediction. We shall then use these scenarios to study the impacts of climate and land use change to 2050 on hydrology, P mobilization, delivery and in-stream processing, informed from new empirical learning and experimentation. Model outputs will then be validated for other catchments in the wider UK (Conwy, Ribble, Tarland) using data from linked projects and our partners. Throughout the project, the outcomes will be tested with stakeholders. This will deliver a locally owned knowledge-based framework for understanding and managing future nutrient transfers from rural catchment systems, and some exciting new science on P transfers.