[Content] Add the Concentrated Leak Erosion Cross-Valley Settlement Screening technical reference manual to the System Response Library

docs/web-applications/system-response/cle-cross-valley-settlement-screening/v1.0/00-document-info.mdx

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+---
+title: Document Info
+reportDate: October 2026
+reportType: Technical Reference
+reportTitle: Concentrated Leak Erosion Cross-Valley Settlement Screening Technical Reference Manual
+reportSubTitle: System Response Library
+reportAuthors: ['Adam Gohs, P.E.']
+reportAbstract: Technical reference documenting the concentrated leak erosion (CLE) cross-valley settlement screening model in the System Response library. The model computes a system response probability (SRP) at each headwater level for concentrated leak erosion through a transverse crack opened at the crest by differential settlement of the embankment across the valley. The flaw assessment converts the normalized crest settlement and the abutment slope, with an optional abutment step, into a localized tensile strain, and from that strain into the probability of a continuous transverse crack, the crack width, and the crack depth. The bottom of the crack gates initiation, and the remaining nodes of the eight-node CLE event tree follow the methods shared by the CLE screening models. The flaw assessment is deterministic, and the model applies simplifications appropriate for screening-level risk analysis.
+reportSubjectTerms: ['CLE', 'Concentrated Leak Erosion', 'Screening', 'Cross-Valley Differential Settlement', 'Transverse Cracking', 'Localized Tensile Strain', 'Crack Depth', 'Event Tree', 'System Response Probability', 'System Response Curve']
+citationGuide: 'U.S. Army Corps of Engineers, Risk Management Center, <i>Concentrated Leak Erosion Cross-Valley Settlement Screening Technical Reference Manual</i>, Lakewood, CO: U.S. Army Corps of Engineers, Risk Management Center, 2026.'
+---
+
+import Link from '@docusaurus/Link';
+import DocumentMetadata from '@site/src/components/DocumentMetadata';
+import NavContainer from '@site/src/components/NavContainer';
+
+<NavContainer
+  link="/web-applications/system-response"
+  linkTitle="System Response Library"
+  document="web-applications/system-response/cle-cross-valley-settlement-screening"
+/>
+
+# Document Information
+
+<DocumentMetadata metadata={frontMatter} />

docs/web-applications/system-response/cle-cross-valley-settlement-screening/v1.0/00-version-history.mdx

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+---
+title: Version History
+---
+
+import NavContainer from '@site/src/components/NavContainer';
+import TableVersionHistory from '@site/src/components/TableVersionHistory';
+
+<NavContainer
+  link="/web-applications/system-response"
+  linkTitle="System Response Library"
+  document="web-applications/system-response/cle-cross-valley-settlement-screening"
+/>
+
+# Version History
+
+<TableVersionHistory
+  versions={['1.0']}
+  dates={['October 2026']}
+  descriptions={['Initial release as an online document.']}
+  modifiedBy={['-']}
+  reviewedBy={['-']}
+  approvedBy={['-']}
+/>

docs/web-applications/system-response/cle-cross-valley-settlement-screening/v1.0/01-preface.mdx

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+---
+title: Preface
+---
+
+import NavContainer from '@site/src/components/NavContainer';
+
+<NavContainer link="/web-applications/system-response" linkTitle="System Response Library" document="web-applications/system-response/cle-cross-valley-settlement-screening" />
+
+# Preface
+
+This document provides a technical reference for the concentrated leak erosion (CLE) cross-valley settlement screening model in the System
+Response library. The model computes a system response probability (SRP) as a function of headwater elevation for concentrated leak erosion
+through a transverse crack that differential settlement of the embankment across the valley opens at the crest. It is a screening-level model: it
+applies simplifications intended to reduce input burden while avoiding false negatives, and any application that performs screening-level risk
+analysis can use it.
+
+The model is one of eight CLE screening models that share one event tree and most of their methods. Those shared methods — the event-tree
+structure, the headwater gate that governs initiation in a crest crack, the failure-pathway conventions behind the continuation and progression
+nodes, and the form of the results — are documented once in the
+[Concentrated Leak Erosion Common Methods Screening Technical Reference Manual](https://usace-rmc.github.io/RMC-Software-Documentation/docs/web-applications/system-response/cle-common-methods-screening/v1.0/model-overview).
+The continuation node is evaluated by the shared continuation method documented in the
+[Continuation (Filter Evaluation) Screening Technical Reference Manual](https://usace-rmc.github.io/RMC-Software-Documentation/docs/web-applications/system-response/continuation-screening/v1.0/model-overview).
+This manual documents what is specific to cross-valley settlement — its flaw assessment, its inputs, how its flaw sets the elevations the
+downstream nodes use, and its assumptions — and refers to the specific chapters of those two manuals for the rest.
+
+The intended audience includes dam safety engineers evaluating whether the model is appropriate for their assessment, and peer reviewers checking
+the technical basis of screening-level results. Readers are assumed to have a general background in internal-erosion risk analysis — event trees,
+concentrated leak erosion mechanics, embankment cracking, and probability concepts — but no familiarity with the software implementation is
+required.
+
+## Document Organization
+
+- **[Model Overview](./02-model-overview.mdx)** — The model's purpose and intended use, a summary of its execution pathway from inputs to results,
+  its engineering basis, a comparison with detailed methods, and its relationship to the shared CLE methods.
+- **[Input Parameters](./03-input-parameters.mdx)** — The inputs specific to cross-valley settlement — the length unit, the dam height, the
+  abutment slope and step, the settlement or year of construction, and the observation of continuous transverse cracking — and a guide to the
+  shared inputs documented in the common methods manual.
+- **[Flaw Assessment](./04-flaw-assessment.mdx)** — The calculation of the normalized settlement, the localized tensile strain with and without
+  an abutment step, the flaw probability, the crack width, the crack depth, and the bottom-of-crack elevation, with a worked example.
+- **[Event Tree](./05-event-tree.mdx)** — How the eight nodes of the CLE event tree are populated for this mechanism at each pool level, and how
+  the SRP is computed.
+- **[Assumptions and Limitations](./06-assumptions-and-limitations.mdx)** — Each assumption specific to this model with its engineering basis, its
+  effect on results, and the conditions under which it may not hold.
+- **[Output and Interpretation](./07-output-and-interpretation.mdx)** — The results the model produces, how to read the system response curve and
+  the flaw-assessment results, and the role of screening results relative to detailed analysis.

docs/web-applications/system-response/cle-cross-valley-settlement-screening/v1.0/02-model-overview.mdx

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+---
+title: Model Overview
+---
+
+import Citation from '@site/src/components/Citation';
+import CitationFootnote from '@site/src/components/CitationFootnote';
+import NavContainer from '@site/src/components/NavContainer';
+import TableReference from '@site/src/components/TableReference';
+import TableVertical from '@site/src/components/TableVertical';
+
+<NavContainer link="/web-applications/system-response" linkTitle="System Response Library" document="web-applications/system-response/cle-cross-valley-settlement-screening" />
+
+# Model Overview
+
+## Purpose
+
+The cross-valley settlement screening model computes a system response curve for concentrated leak erosion through a transverse crack caused by
+differential settlement of the embankment across the valley. The system response probability (SRP) at each headwater level is the conditional
+probability of breach of the embankment by concentrated leak erosion through such a crack, given that pool level.
+
+An embankment settles more where the fill beneath the crest is thicker, so the crest settles most over the deepest part of the valley and least
+near the abutments. Where the abutment is steep, or where it carries an abrupt step, the settlement changes rapidly along the
+crest and stretches the fill near the top of the embankment. If that stretching exceeds what the fill can sustain, a transverse crack opens at the
+crest and extends some depth into the embankment. Once the pool rises above the bottom of the crack, water can flow through it, and the crack
+becomes the flaw from which concentrated leak erosion can develop.
+
+## Intended Use
+
+The model is a screening-level assessment of concentrated leak erosion through a cross-valley settlement crack. Like the other CLE screening
+models, it makes simplifying and generally conservative assumptions with two goals (see the
+[Intended Use](https://usace-rmc.github.io/RMC-Software-Documentation/docs/web-applications/system-response/cle-common-methods-screening/v1.0/model-overview#intended-use) section of the common
+methods manual):
+
+- **Preventing false negatives** — The flaw probability is read from the more conservative of two available relationships, the one for a pool
+  above the period of record, and initiation is taken as certain once the pool rises above the bottom of the crack.
+- **Reducing input burden** — The flaw assessment needs only the dam height, the abutment slope, an optional abutment step, and either the
+  measured settlement or the year of construction, from which a default settlement is assigned.
+
+The model is not intended for detailed or semi-quantitative risk assessments of transverse cracking. Its flaw assessment uses tabulated
+relationships over a limited range of settlement and abutment slope (see [Flaw Assessment](./04-flaw-assessment.mdx)), and its initiation
+treatment does not analyze the hydraulics of the crack.
+
+## How the Model Works
+
+The model executes the three stages common to the CLE screening models (see
+[How the Model Works](https://usace-rmc.github.io/RMC-Software-Documentation/docs/web-applications/system-response/cle-common-methods-screening/v1.0/model-overview#how-the-model-works) in the common
+methods manual), with a flaw assessment specific to cross-valley settlement:
+
+1. **Flaw assessment** — The maximum post-construction crest settlement, or a default from the year of construction, is normalized by the dam
+   height. The normalized settlement and the abutment slope give the localized tensile strain at the crest, interpolated from tables for an abutment
+   without a step or, when a step is described, from tables for three relative step heights. The strain then gives the probability of a continuous
+   transverse crack, the crack width, and, through a relationship between crack width and crack depth, the depth of the crack below the crest and
+   so the bottom-of-crack elevation. An observation of continuous transverse cracking sets the flaw probability to 1.0 (see
+   [Flaw Assessment](./04-flaw-assessment.mdx)).
+2. **Pathway description** — The model applies the user's description of the failure pathway along the crack, taken at the bottom-of-crack
+   elevation: the top of the first filter the pathway meets, the materials of the full and the below-filter pathways, and the upstream
+   seepage-limiting elements and the top of any wall (see [Input Parameters](./03-input-parameters.mdx#shared-inputs)).
+3. **Event-tree assembly** — At each headwater level, the model evaluates the eight nodes of the CLE event tree and multiplies them. Initiation
+   steps from zero to 1.0 where the pool rises above the bottom of the crack; continuation, roof support, and flow limitation change where the pool
+   crosses the top of a filter or of a wall (see [Event Tree](./05-event-tree.mdx)).
+
+Every step is deterministic. The only part of the calculation that can involve sampling is the continuation probability, when the shared
+continuation method evaluates the filter by its route through the soil classifications of the base and filter soils (see
+[Method Selection and Governing Base Soil](https://usace-rmc.github.io/RMC-Software-Documentation/docs/web-applications/system-response/continuation-screening/v1.0/method-selection-and-governing-base-soil)
+in the continuation manual).
+
+## Physics Basis
+
+The model combines the following engineering relationships:
+
+- **Localized tensile strain from settlement and abutment geometry** — tabulated relationships between the normalized crest settlement, the
+  abutment slope, the relative height of an abutment step, and the localized tensile strain at the crest (see
+  [Flaw Assessment](./04-flaw-assessment.mdx#localized-tensile-strain))
+- **Flaw probability and crack width from the localized tensile strain** — tabulated relationships between the strain, the probability of a
+  continuous transverse crack, and the crack width (see [Flaw Assessment](./04-flaw-assessment.mdx#flaw-probability))
+- **Crack depth from crack width** — an empirical relationship attributed to Pierson (2023) (see
+  [Flaw Assessment](./04-flaw-assessment.mdx#crack-depth-and-bottom-of-crack-elevation))
+- **Initiation in an open crest crack** — the headwater gate shared by the crest-crack models, documented in the
+  [Crest-Crack Models: Headwater Gate](https://usace-rmc.github.io/RMC-Software-Documentation/docs/web-applications/system-response/cle-common-methods-screening/v1.0/initiation#crest-crack-models-headwater-gate)
+  section of the common methods manual
+- **Continuation, roof support, crack filling, and flow limitation** — the failure-pathway conventions and the tabulated progression
+  probabilities of Fell et al. (2024) <Citation citationKey="Fell2024" />, documented in the
+  [Failure Pathway and Progression](https://usace-rmc.github.io/RMC-Software-Documentation/docs/web-applications/system-response/cle-common-methods-screening/v1.0/failure-pathway-and-progression)
+  chapter of the common methods manual, with filter evaluation by the shared continuation method
+
+## Comparison with Detailed Models
+
+In a detailed risk analysis, the likelihood, width, and depth of a transverse crack are estimated by the risk team from the totality of the
+evidence, and initiation in the crack is assessed with a shear stress analysis of the crack geometry, for example with the
+[Vertical Rectangular Crack](/docs/toolbox-technical-manuals/internal-erosion-suite/concentrated-leak-erosion-initiation/v1.0/vertical-rectangular-crack)
+or [Vertical Triangular Crack](/docs/toolbox-technical-manuals/internal-erosion-suite/concentrated-leak-erosion-initiation/v1.0/vertical-triangular-crack)
+geometry of the Concentrated Leak Erosion Initiation toolbox. <TableReference tableKey="cle-cross-valley-screening-table-1" /> summarizes the differences.
+
+<TableVertical
+  tableKey="cle-cross-valley-screening-table-1"
+  alt="Comparison of the cross-valley settlement screening model and detailed methods"
+  caption="Comparison of the cross-valley settlement screening model and detailed methods."
+  headers={[[{ value: 'Aspect' }, { value: 'Screening Model' }, { value: 'Detailed Methods' }]]}
+  columns={[
+    [
+      'Purpose',
+      'Settlement',
+      'Flaw probability',
+      'Crack width and depth',
+      'Initiation',
+      'Progression',
+    ],
+    [
+      'Screening-level risk assessment',
+      'Measured maximum settlement, or a default from the year of construction',
+      'Tabulated from the localized tensile strain, with an observation override',
+      'Tabulated width from the strain; depth from an empirical width-depth relationship',
+      'Certain once the pool rises above the bottom of the crack',
+      'Tabulated roof-support, crack-filling, and flow-limitation probabilities',
+    ],
+    [
+      'Detailed risk analysis',
+      'Site settlement records, interpreted by the risk team',
+      'Estimated by the risk team from the totality of the evidence',
+      'Estimated from cracking analysis, with sensitivity analysis',
+      'Shear stress analysis of the crack geometry',
+      'Assessed by the risk team, informed by the same tables',
+    ],
+  ]}
+/>
+
+## Relationship to the Common CLE Methods
+
+The model is one of the four crest-crack models of the CLE family, with settlement adjacent to a wall or cliff, desiccation cracking, and frost
+cracking (see [The Two Model Groups](https://usace-rmc.github.io/RMC-Software-Documentation/docs/web-applications/system-response/cle-common-methods-screening/v1.0/model-overview#the-two-model-groups)
+in the common methods manual). It differs from the other three in its flaw assessment: it is the one CLE model that does not use risk-factor and
+likelihood-factor scoring, estimating the flaw probability instead from the settlement-based relationships documented in
+[Flaw Assessment](./04-flaw-assessment.mdx). It is also the one crest-crack model that derives the crack depth from a crack width rather than
+from tabulated depths.
+
+Everything downstream of the flaw assessment follows the common methods: the eight-node event tree, the headwater grid, the initiation gate, the
+pathway gates on the top of the filter and the top of a wall, and the progression tables. This manual does not repeat them; [Event Tree](./05-event-tree.mdx)
+states how each node is populated for this model and links the section of the common methods manual that documents it.
+
+<CitationFootnote />